Exergy and thermo-economic analysis of ghee production plant in dairy industry

Energy 167 (2019) 602e618

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Exergy and thermo-economic analysis of ghee production plant in dairy industry Gurjeet Singh a, *, P.J. Singh a, V.V. Tyagi b, P. Barnwal c, A.K. Pandey d a

Department of Mechanical Engineering, Punjab Engineering Collage, Chandigarh 160012, India School of Energy Management, Shri Mata Vaishnao Devi University, Jammu 180001, India c Dairy Engineering Division, ICAR-National Dairy Research Institute, Karnal 132001, India d Research Centre for Nano-Materials and Energy Technology (RCNMET), School of Science and Technology, Sunway University, No. 5, Jalan Universiti, Bandar Sunway, Petaling Jaya, 47500, Selangor Darul Ehsan, Malaysia b

a r t i c l e i n f o

a b s t r a c t

Article history: Received 7 March 2018 Received in revised form 8 July 2018 Accepted 23 October 2018 Available online 7 November 2018

The India’s annual milk and ghee production are approximately estimated as 160 MT and 1.72 MT respectively. India has the largest production of Ghee in the dairy Industry worldwide. Ghee consumption in India is 28% annually after fluid milk i.e. 44% due to high consumer demand. The butter churner, butter melter, ghee boiler and ghee clarifier are the key subunits of ghee production plant. The dairy industry is characterised by high energy consumption for production of Ghee and Butter in the country. The thermo-economic analysis and thermodynamic derivatives calculated in this study. The value of the universal exergy efficiency and specific exergy destruction of the plant was found as 34.21% and 438.61 kJ/kg respectively. The cost rate of exergy destruction for the entire plant was calculated as 3270.68 R/H; 39% of which was contributed by boiler for ghee production (ghee boiler). The highest value of percentage relative cost difference was associated with butter melter (97.29%) followed by butter churner (96.73%). The thermo-economic factor butter churner (8.00%) and ghee boiler (1.09%) revealed that impact of capital investment was more influential in former while exergetic degradation appeared to be more noticeable in latter. © 2018 Elsevier Ltd. All rights reserved.

Keywords: Energy Exergy Exergy efficiency Exergy destruction Thermo-economic

1. Introduction Ghee is an Indian name for clarified butter fat (anhydrous milk fat) which is produced by heat desiccation of butter [1]. In process of ghee production, the traces of moisture are completely eliminated from multiphase emulsion of milk fat globules and water i.e. butter, which is materialised by churning of cream in a butter churner mechanism [2]. The systematic procedure of ghee production is as follows: milk cream pasteurisation and its subsequent storage at less than 10
C temperature, churning the milk cream in the butter churner for nearly 45 min, for its conversion into solid butter which is melted in a butter melter using thermal energy from steam followed by heating the melted butter in a ghee boiler for sufficient period of time to get the ghee in liquid form. The ghee thus produced passed through clarifier to remove presence to sludge or crud in it [3]. India produces 19.54% of world’s annual milk production i.e. 817 MT, but numerical value of its capability of

* Corresponding author. E-mail address: [email protected] (G. Singh). https://doi.org/10.1016/j.energy.2018.10.138 0360-5442/© 2018 Elsevier Ltd. All rights reserved.

conversion from raw milk to value added product is very low [4]. The annual growth in production and consumption of ghee was estimated as 6.4% and 2.5% respectively [5]. The per capita butter and ghee consumption in India are estimated as 3.9 kg and 15.6 kg per year respectively [6]. World milk production is projected to increase at an average rate of 1.8% during the next 10 years compared to 2.3% average annual growth experienced in the past decade. The globalization of dairy industry, international demand patterns, and economic prosperity has led to paradigm shift of international dairy markets from being supply driven to demand driven [7]. The prospects of sustained high prices for dairy products is creating incentives for investment expansion and restructuring of local dairy industries [8]. India is ranked at eighteenth position in global milk food exports with a 0.68% share in international trade; in which contribution of Ghee is determined as 15%. The world dairy exports have increased from US$27.61 billion in 2001 to US$84.46 billion in 2013. In 2015, India’s dairy exports grew to US$203.80 million compared to its imports of US$128.30 million and emerged as the net exporter of dairy products [9]. Going by the aforementioned figures; it could be easily ascertained that most of the energy demands of food processing industry are met primarily

G. Singh et al. / Energy 167 (2019) 602e618

Nomenclature AC 

Annual Cost of Component (R)

C c CE cf,k cp,k cp CRF DD,k

: Cost Flow Rate (R/H) Exergetic Cost (R/MJ) Chemical Exergy Unit Exergetic Cost of Fuel (R/MJ) Unit Exergetic Cost of Product (R/MJ) Specific Heat (kJ/kg K) Capital Recovery factor Cost Rate of Exergy Destruction (R/H)

E

Energy (kJ/s)





EL Eb,k Exb, k: EF, k: ExF, k: ex 

Ex 

Ex D EIP ExIP f F h H I J kWh 

m MF PE PEC PRCD PWF PW

Energy Loss Rate (kW) Relative Energy Destruction Ratio (%) Relative Exergy Destruction Ratio (%) Energetic Factor (%) Exergetic Factor (%) Specific Exergy (kJ/kg) Exergy Rate (kW) Exergy Destruction Rate (kW) Energy Improvement potential (kW) Exergy Improvement Potential (kW) Exergoeconomic Factor of Component Fuel Exergy Rate (kW) Specific Enthalpy (kJ/kg) Hour Interest rate (%) Ratio of salvage value Kilowatt Hour : Mass Flow Rate (kg/s) Milk Fat Physical Exergy Purchase Equipment Cost (R) Percentage Relative Cost Difference Present Worth Factor Present Worth of Component (R)

by huge amount of fossil fuel consumption. The scenarios of growth, production, consumption and international trade of dairy products suggests that futuristic modes of growths as well as profitability will be dependent upon many factors such as energy management, degree of renewability, population rise, and demographic changes etc. Therefore, it has become highly imperative to involve ultra modern tools such as exergoeconomic, pinch and life cycle analyses for accurate estimation of cost-energy matrix as well as overall performance of the plant [10]. In continuation to the same, exergy analysis is adjudged to be meaningful and realistic platform for qualitative and quantitative estimation of energy requirements in an energy system. The same has been extensively explored in various different fields, in order to improve design characteristics, achieve optimal performance of energy system, and modify the existing architecture of the thermal system to materialise optimum cost benefit [11e15]. Additionally, Sorgiwan and Ozilgen [16] developed platform for calculation of energy, exergy consumption and CO2 emissions in production, processing, transport activities of plain yogurt production plant. In another energetic evaluation; Waheed et al. [17] found that in 1 tonnes of orange processing, the proportion of thermal energy consumption outweighed the electrical energy counterpart, whereas contribution of

r R/MJ T s S S SI TCI TOCR TPD

n W 

ZT 

Z CI 

Z OM

603

Percentage Relative Cost Difference (%) Rupees per Mega-joule Temperature (K) Specific Entropy (kJ/kg K) Entropy (kJ/K) Salvage Value (R) Sustainability Index Total Cost of Investment (R) Total Operating Cost Rate (R/H) Tons per day Specific Volume (m3/kg) Work Rate (kW) Levelized Cost Rate associated with Capital Investment and Operation & Maintenance cost (R/H) Levelized Cost Rate associated with Capital Investment (R/H) Levelized Cost Rate associated with Operation & Maintenance cost (R/H)

GREEK LETTERS Rg Universal Gas Constant (8.314 kJ/mol K) r Density (kg/m3) h Energy Efficiency (%) J Exergy Efficiency (%) 0 Dead State R Indian National Rupee SUBSCRIPTS BM Butter Melter BSP Butter Supply Pump CSP Cream Supply Pump CST Cream Storage Tank GB Ghee Boiler in Inlet k Any Component out Outlet T Total

manual energy was comparatively meagre. Further, in a similar kind of attempt Dowlati et al. [18] identified an ice cream production factory to perform the exergetic survey and pinpointed the thermodynamic deficiencies in subunits of the plant. Furthermore, Mojarab and Aghbashlo [19] exercised concerted efforts to unearth the exergetic significance of each subunit of drinking yogurt production plant. The exergy deficiency and specific exergetic destruction were ascertained to be 31.21% and 3185.36 kJ/kg respectively. Similarly, in an another thermodynamic analysis, Nasiri et al. [20] applied exergy gauge on industrial scale ultra filtrated cheese production unit located in Tehran, Iran, wherein cumulative exergy destruction of thermal and electrical energy consuming units was reported as 149.24 kW and 64.57 kW respectively. As far as sustainability of food technologies with regard to food waste were concerned; Goot et al. [21] performed a broad survey of food processing technologies to understand and underline the origin of food waste generation, inefficient food processing techniques, thermal behaviour, innovative food production technologies conjoined with related imperfections. In view of increasing environmental degradation, the approaches which conform to ultramodern design of mechanical system and improve sustainable behaviour of food production units; are serious need of

604

G. Singh et al. / Energy 167 (2019) 602e618

hour. In a recent work, performed in a sugar production plant; Taner and Sivrioglu [22] identified raw juice production, purification, stiffening, refining granulation are the key activities related to processing of sugarcane juice apart from steam generation. In extension of the similar exercises, Garg et al. [23] determined deficiencies and improvements in a sugar processing and clarification plant. The raw juice processing subunit reflected an energy and exergy deficiency of 40% and 17% respectively. As far as thermoeconomic analysis of energy systems were concerned; Taner and Sivrioglu [24] performed the same upon turbine plant integral to a sugar production plant. The cost per unit exergy and electricity were established to be 3.142 $/kW and 0.87 $/kW respectively for a repayment period of 4.32 years. In perpetuation of the same; Erbay and Koca [25] executed exergoeconomic analysis of cheese powder production unit. For an inlet temperature in the range of 1600Ce230
C, the exergy efficiency and exergoeconomic factor for the drying chamber had reported a variation of 4.25% and 3.13% respectively, On a similar note, Tsatsaronis G. [26] developed some quite intriguing outcomes associated with thermo-economic characteristics of energy system which otherwise was never discovered by traditional tools of economic evaluation. In prolongation to the existing economic analysis conjoined with energy analysis of subunits of the plant, Lazzaretto and Tsatsaronis [27] understood significance of unification of exergy and economic derivatives. In this platform; cost balance equations were solved in connection with auxiliary equations to procure monetary figures of exergy demolition in a process flow framework. Despite having a variety of studies pertaining to thermodynamic and thermo-economic analysis of different kinds of food production and processing units; there is still severe dearth of research works related to production and processing of value added dairy products, such as milk cream, butter and ghee etc, to the best knowledge of author. Further, the scope of waste heat recovery and heat integration apart from productivity enhancement, improvement in overall sustainability of plant, had not been comprehensively addressed before [28e35]. Moreover, the conventional way of thermal analysis of any energy system had not given an extensive coverage to possible extent of economic or energy savings; particularly for the plants where aforementioned scopes are not effectively brought to the light [36e41]. In view of huge energy requirement in dairy processing industry, the exact estimation of energy resource consumption along with its economic value is the serious need of hour; the knowledge of which would help plant designer and mangers to evolve strategies for achievement of optimal plant performance. In light of same, the present study is carried out with a motive to highlight the scope of heat recovery, productivity enhancement, sustainability increment as well as possible innovation in the present technology along with an approximate measure of monetary benefit that could be secured by meeting above stated requirements. Further, an exhaustive estimation of thermodynamic and thermoeconomic derivatives such as universal exergy efficiency, specific exergy destruction and cost rate of exergy destruction were carried out. The percentage relative cost difference, thermoeconomic factor, total operating cost rate will act as a basis for fruitful estimation of thermoeconomic behaviour in an industrial scale ghee production plant of the dairy industry in India. 2. Plant description and methodology 2.1. Plant description The ghee production plant of a dairy industry is presented in Fig. 1 which consists of cream storage tank, cream supply pump, butter churner, solid butter transfer trolley, butter melter, liquid

Fig. 1. Schematics of an actual Ghee Production Plant.

butter supply pump, ghee boiler, ghee supply pump, ghee storage tank, ghee clarifier, balance tank and final packing. The raw milk is received at raw milk reception desk (RMRD) of dairy factory, where necessary chilling i.e. < 4
C is provided to it using plate heat exchanger arrangement. The milk is then pumped to pasteurisation unit where, by suitable adjustment of control valves, milk cream with variable fat contents is separated. The cream separation activity usually carried out in the temperature range of 550e57
C, as the said temperature range is conducive for performing the same. The remaining skim milk is passed through the pasteurisation circuit to achieve complete pasteurisation of skim milk. However, the cream with requisite fat content may be recombined to acquire desired level of fat in the milk. The cream obtained by cream separation process may contain different contents of fat as it purely depends upon fat content present in the raw milk. The cream also obtained in this manner is prone to pathogenic disorder if not properly pasteurised. Thus, in order to protect the cream from attack of micro-organisms; the pasteurisation of milk cream is carried out in the temperature range of 85e90
C for different residence time settings. The complete pasteurisation of milk is characterised by phosphate test for inactivation of coliform bacteria at residence time - temperature conditions of 15s 72
C. Similarly, complete pasteurisation of milk cream is characterised by storch’s peroxide test, wherein the enzymatic activity in cream is completely arrested by heating and holding the milk cream at 90
C for nearly 1s of time [42]. The cream or milk pasteurised in this manner is stored for production of other value added products such as flavoured milk, ice cream, butter and ghee etc. The cream is received in the storage tank at a temperature condition of less than 10
C and stored for a sufficient period of time till it is used for specific purposes. The cream at above specified temperature condition is pumped into a butter churner, which contains baffles/beaters for generation of turbulations inside it. The butter churner rotates at 40 rpm in such a manner that after rotation for 45 min it produces butter and butter milk. During this process, cream undergoes phase inversion as the fat globule membranes are dispersed, globule coalesce to form clarified butter and oil leaks out to form continuous phase [43] i.e. butter milk. The butter is passed on to a butter melter whereas butter milk is stored in some other storage tank. The butter melter contains coils all along its length through which hot water is passed. The activity helps in melting of butter and thereby temperature rise up to 80
C is obtained. The melted butter is pumped to a ghee boiler where butter is heated for sufficient span of time and gets converted into clarified butter i.e. ghee. Finally, the ghee produced in this manner is clarified in a ghee clarifier to remove any impurity or curd formation present in it. The pure ghee prepared in this manner is stored in a storage tank and

G. Singh et al. / Energy 167 (2019) 602e618

further, packed into suitable size bags for its final disbursement to the market.

605



j¼

Exout 

 100

(v)

Exin 2.2. Methodology In order to accomplish the objective of exergy and exergoeconomic analysis, the required data was acquired from Dairy Unit located in northern part of India, which has a ghee production capability of 3 TPD. The technical data used for the aforementioned analysis was measured and recorded by the mechanical manpower of the dairy factory, continuously for the year 2017. The ensuing assumptions were incorporated in the current analysis:

The physical, chemical and total value of exergy rates of different materials at all the state points of flow streams were estimated as follows:

       T þ nðP  P0 Þ Ex ¼ m cp T  T0  T0 ln T0 



Ex ch ¼ mn

"

X X xi εi þ Rg T0 xi lnðxi Þ i

1. The whole of the plant and its ingredients were operated in a steady state condition. 2. The kinetic and potential energy magnitude were ignored owing to negligible contribution towards total exergy [44]. 3. The dead state temperature and pressure were considered as 298.15 K and 101.325 kPa respectively. 4. The exergy destruction due to crud formation was disregarded due to its negligible content. 5. The change in surrounding temperature was disregarded. 6. The contribution of fat formation of exergy was negligible and the same was disregarded [44].

3. Thermodynamic analysis Basically, there are two laws of thermodynamics which on its application to any energy system generate energetic and exergetic information. The exergy principle target upon recovery of information related to energy degradation during product processing which otherwise could not be procured by first law of thermodynamics. Therefore, it could be clearly understood that second law enables a plant manger to locate the domains of exergy destruction and improvement thereof.





(vi)

# (vii)

i 

Ex T ¼ Ex ph þ Ex ch

(viii)

The key thermodynamic derivatives for all the subunits of the plant have been tabulated in Table 1. Further, the mathematical formulations for energy and exergy for each of the constituents of the plant is given in Table 2.

3.2. Thermo-economic analysis In current study; the economic data is secured from the actual quotation of the supplier during the computation of the cost rates at various positions of the processing plant. In order to obtain the perfect results; costs of main units were taken into consideration and cost allotment to subsystems, operational and maintenance expenditures were procured from the maintenance section of the

Table 1 Key Factors related to Energy and Exergy Analysis [45,46]. S. No Name of the Factor Pertaining to Energy Analysis 1 Energy efficiency



h¼

Eout;k 

 100

Ein;k

3.1. Energy and exergy analysis The following mass balance equation was incorporated into our study to perform energy and exergy analysis.

X



min ¼

X



mout

(i)

The subscript ‘in’ and ‘out’ stand for input and output respectively. The general energy equilibrium equation is expressed as follows: 



Q net;in  W net;out ¼

X



mout hout 

X



min hin

h¼



 100

(iii)

Ein The general exergy balance is expressed as: 



Exin  Exout ¼

X ExD

The second law efficiency is generally defined as:

(iv)



EL;k ¼Ein;k  Eout;k

3

Energy Improvement Potential

EIP;k ¼ ð1  hI Þ  EL;k

4

Relative Energy Destruction Ratio

5

Energetic Factor

6

Energy Efficiency of Plant







EL;k Eb;k ¼ P   100 EL;k 

Ein;k Ef ;k ¼ P   100 Ein;k P E hp ¼ P out;k  100  Ein;k

Name of the Factor Pertaining to Exergy Analysis 1 Exergy efficiency



j ¼

Exout;k

 100



Exin;k 2 3

Exergy Destruction Exergy Improvement Potential

4

Relative Irreversibility Factor

5

Exergetic Factor

6

Sustainability Index

7

Exergy Efficiency of Plant



X Eout



Energy Destruction

(ii)

The first law efficiency is defined as the ratio of energy output to energy input as:



2







Ex D ¼ Ex in  Ex out 



Ex IP ¼ ð1  jÞ  Ex D 

Ex D;k  100 Exb;k ¼ P  Ex D;T 

 Ex in;k  100 Ex G;k ¼ P  Ex in;k 1 SI ¼ 1j P Ex Jp ¼ P out;k  100  Exin;k

606

G. Singh et al. / Energy 167 (2019) 602e618

Table 2 Energetic and Exergetic Formulations for subunits of Ghee Production Plant. S.NO 1

COMPONENT

THERMODYNAMIC FORMULATIONS 











m1 þ m12 ¼ m2 þ m13 





EL ¼ ðE1 þ E12 þ W22 Þ  ðE2 þ E13 Þ 









Ex D ¼ ðEx 1 þ Ex12 þ W22 Þ  ðEx2 þ Ex 13 Þ 

h¼



E2 þ E13





E1 þ E12 þ W22 



j ¼

2

 100

Ex2 þ Ex 13





Ex1 þ Ex12 þ W22



 100



m2 ¼ m3 





EL ¼ E2 þ W23  E3 





ExD ¼ Ex 2 þ W23  Ex3 

h¼

E3



E2 þ W23

 100



j ¼

3

Ex3



 100

Ex2 þ W23







m3 ¼ m4 þ m27 









EL ¼ ðE3 þ E24 Þ  ðE4 þ E27 Þ 









Ex D ¼ ðEx3 þ Ex24 Þ  ðEx 4 þ Ex 27 Þ

h¼ j ¼

4









E4 þ E27

 100

E3 þ E24 







Ex4 þ Ex 27

 100

Ex 3 þ Ex 24















m4 þ m14 þ m15 ¼ m5 þ m16 







EL ¼ ðE4 þ E14 þ E15 þ W31 Þ  ðE5 þ E16 Þ 











ExD ¼ ðEx 4 þ Ex 14 þ Ex 15 þ W31 Þ  ðEx 5 þ Ex 16 Þ 

h¼







E5 þ E16 

E4 þ E14 þ E15 þ W31 

j ¼



 100



Ex 5 þ Ex 16 



Ex 4 þ Ex 14 þ Ex 15 þ W31

 100

G. Singh et al. / Energy 167 (2019) 602e618

607

Table 2 (continued ) S.NO 5

COMPONENT

THERMODYNAMIC FORMULATIONS 



m6 ¼ m7 





EL ¼ E6 þ W22  E7 





ExD ¼ Ex6 þ W22  Ex 7 

h¼

E7



E6 þ W30 

j ¼

6

 100



Ex 7  Ex6  100 W30

















m6 þ m17 þ m26 ¼ m7 þ m18 þ m28 EL ¼ ðE 



6 





þ E17 þ E26 Þ  ðE 





7



þ E18 þ E28 Þ 





ExD ¼ ðEx 6 þ Ex 17 þ Ex26 Þ  ðE x7 þ Ex 18 þ Ex28 Þ 

h¼ j ¼

7





E7 þ E18 þ E28 



 100



E6 þ E17 þ E26 









Ex7 þ Ex18 þ Ex28 

Ex 6 þ Ex 17 þ Ex 26

 100





m7 ¼ m8 





EL ¼ E7 þ W29  E8 





Ex D ¼ Ex7 þ W29  Ex8 

h¼

E8



E7 þ W29 

j ¼

8

 100



Ex8  Ex7  100 W29















m8 þ m19 þ m20 ¼ m9 þ m21 EL ¼ ðE 



8 





þ E19 þ E20 Þ  ðE 



9



þ E21 Þ 



ExD ¼ ðE x8 þ Ex 19 þ Ex20 Þ  ðE x9 þ Ex21 Þ 

h¼



E9 þ E21







j ¼

9



E8 þ E19 þ E20 

 100



Ex 9 þ Ex21 



Ex8 þ Ex19 þ Ex 20

 100





m9 ¼ m10 





EL ¼ E9 þ W30  E10 





ExD ¼ Ex 9 þ W30  Ex 10 

h¼





j ¼

E10

E9 þ W30

 100



Ex10  Ex9  100 W30

(continued on next page)

608

G. Singh et al. / Energy 167 (2019) 602e618

Table 2 (continued ) S.NO

COMPONENT

THERMODYNAMIC FORMULATIONS 



10

m10 ¼ m11 





EL ¼ E10  E11 





ExL ¼ Ex 10  Ex 11 

h¼

E11 

 100

E10 

j ¼

Ex 11 

 100

Ex 10

concern. The economic aspects include the hourly levelised cost rate of capital investment cost, purchase equipment cost, operating and maintenance cost rate and the total cost rate of the ghee production plant and its sub components. The exergoeconomic evaluation consists of the discernment of cost flow rates at each step of complete processing unit i.e. from the processing of unprocessed resources to resultant output [45,46]. In the current work, specific exergy costing (SPECO) method was instituted to secure cost matrix of the whole plant. As per the mentioned scheme, fuels and products were categorically defined by exergy introduction to and expulsion from each matter and energy influx and outflux. The three steps involved in this kind of examination were as follows: 1. Calculation of exergy out fluxes 2. Quantification of Input (fuel) and Output (product) exergy value for each of the constituents 3. Fabrication of mathematical expressions for cost balance exercises. In order to discern exergy costing characteristics, a cost is merged with each exergy stream. Exergy transmission equations for input and output of the matter by power and heat transferral rates may be written as: 



C i ¼ ci Ex i 

(ix)



C e ¼ ce Ex e 

(x)



C w ¼ cw Ex w 

(xi)



C q ¼ cq Ex q

(xii)

For the plant units, receiving electrical work and transferring heat from the surface, we may write the thermo-economic equilibrium equation as [45,46].

X i



ci Ex i







þ cw Ex w þ Z k ¼

X



ce Ex e





þ cq Ex q

The sum total of levelised cost rate for the capital investment as well as operation and maintenance cost is represented as: 



This equation reflects that sum total cost of exiting energy streams is numerically equal to the cost of incoming exergy streams in addition to capital and other costs. In cost equilibrium equations all the terms are on positive side. For n number of exergy outgoing streams, there will be an n-1 number of auxiliary equations which italicize F and P postulates of SPECO technique. The F proposition proclaims that the undivided cost adjoined with exergy discharge must be equal to cost at which this exergy is invested into the same stream. The P concept elucidates that each exergy unit injected into any stream is attached to the products at the same average cost cp which is decided by cost balance equations carved out by F theory. In the present section, exergetic cost equilibrium equations and correlated auxiliary equations were lined up for each subsystem of ghee production plant.

(xiv)

The hourly levelised cost rate for each of the constituents of the plant is calculated by the algorithm explained in the following six systematic steps. The present worth of the ghee plant under consideration is represented by

PW ¼ TCI  S  PWF

(xv)

where, TCI of the total capital investment at the initial stage which was Rs 1300000, S is the salvage value of the plant which is given the following relation

S ¼ TCI  J

(xvi)

The term J, indicate that ratio of salvage value i.e. which is 8% in the present analysis. Further, mathematical representation of single payment present worth factor (PWF) or single payment discount factor is given by following relationship.

PWF ¼

1 ð1 þ iÞn

(xvii)

wherein, annual interest rate and the number of years for which the facility is operational; are denoted by i and n; the value of the same are given as 10% and 10 years. Furthermore, annual cost of subunit is given by the following equation.

AC ¼ PW  CRF

(xviii)

The term CRF is the capital recovery factor in the aforementioned equation, the mathematical representation of which is by equation given as follows:

(xiii)

e



Z T ¼ Z CI þ Z OM

CWF ¼

iði þ 1Þn ð1 þ iÞn  1

(xix)

The operational and maintenance cost (O&M) of plant is calculated as Rs. 432900, and the plant is operation for 300 days and the production activity is continued for 7 h in a day. Thus, the total number of hours for which the plant is under operational condition, is computed as 2100 h for one year. The annualised equipment cost of the ghee production system is given by the following mathematical equation.

  AC PEC P ZT;k ¼ ð1 þ 4Þ t PEC

(xx)

where, PEC, AC and t are purchase equipment cost, annual cost of the subunits and total number of operational hour in a year

G. Singh et al. / Energy 167 (2019) 602e618

respectively. From the above mentioned steps of algorithm, the hourly levelised cost of capital investment ZCI;k ðR=HÞ as well as operation and maintenance cost ZOM;k ðR=HÞ of the plant is quantified to be 97.54 ðR=HÞ and 32.19 ðR=HÞ Further, the total levelised cost ZT;k ðR=HÞof the ghee production plant is determined as 129.73 ðR=HÞ.

3.2.1. Performance parameters In the present section, the main parameters associated with thermodynamic and thermo-economic evaluation of each subunit as well as that of the plant has been described in detail. The average cost per unit exergy for the fuel and product for the component k was clearly explicated by using equations given as follows:

609

optimum equilibrium between thermal deficiency and capital investment cost. The objectives of thermo-economic evaluation are as follows: 1. To diagnose the orientation and intensity of thermal degradation as well as losses in combination with economic framework for performance enhancement of the plant. 2. To have a clear cut estimation of exergy cost, cost per unit exergy and manufacturing cost of the resultant output. 3. To help in the formulation of technical and economical architecture for better performance of the plant. 4. To pinpoint and investigate various different choices and substitutes with lesser thermal deficiency. 5. To calibrate the cost consolidated within exergy destruction and various cost-related shortages in an energy system.



cf ;k ¼

C f ;k

(xxi)



Ex f ;k 

cp;k ¼

C p;k

(xxii)



Ex p;k 



where, C f ;k and C p;k are the mean unit cost of fuel and product respectively. In order to materialise the thermodynamic analysis in combination with economic constraints and variables for each component of the plant, the indices such as Thermoeconomic 

Factor (fk), Cost Rate of Exergy Degradation (DD;k ) and Percentage Relative Cost Difference (rk) were estimated by involving the relations provided in the Table 3. The thermo-economic factor is the most prominent index of thermo-economic evaluation which basically line up all the subunits of the plant as per their thermo-economic ranking i.e. weigh up the impact of capital investment cost or cost of energy demolition on performance of each subunit. The costs merged with processing of material as well as ingrained thermodynamic deficiencies are computed from viewpoints of evaluation of their thermo-economic merits. Further, apart from calculation of destruction cost, the relative qualitative worthiness of the each constituent is effective gauged by the aforementioned technique. The percentage relative cost difference of any component diagnoses the rise in monetary expenses in processing of a material from its raw shape to final product. Obviously, PRCD act as a unique index in judgement of technical inadequacies along with manifestation of probable causes of shortfall in optimum performances. The cost configuration projected by exergoeconomic evaluation of all the components of the plant assist in judgement of impact of investment cost or exergy destruction cost on overall characteristics of the plant. In nutshell, the analysis nailed down the requirement of an

Table 3 Key factors related to thermo-economic analysis [45,46]. S.No

Name of the Factor

1

Percentage Relative Cost Difference

Mathematical Representation 

rk ¼ 2 3

Cost Rate of Exergy Destruction



C f ;k  C p;k 

C f ;k



 100



DD;k ¼ cf ;k  Ex D;k 

Thermo-economic Factor fk ¼



Zk



Z k þ cf ;k  Ex D;k

 100

Further, the mathematical formulations for exergy cost rate balance equations for each of the constituents of the plant is given in Table 4. In addition to above discussed formulations, the specific heat and specific volume of milk components could be displayed as a function of the processing temperature. These equations reported about the values of specific heat and specific volume as given in Table 5. Accordingly, subsequent equations were employed to compute the unspecified specific heat capacities and the specific volume of milk derivatives at distinct points of the plant respectively.

cp ¼

X Yi  cp;i

(xxiii)

i

n¼

XXi i

(xxiv)

ri

Further, the composition of milk and its derivatives used in computation of specific heat capacity and specific volume is given in Table 6.

3.3. Uncertainty analysis The uncertainty analysis was accomplished using the strategy developed by the Holman [48] to manifest the replication and characterization of exploratory figures.

 U¼

vF vF vF u þ u …þ un vz1 1 vz2 2 vzn

 (xxv)

4. Result and discussion 4.1. Specific chemical exergy of milk and its derivatives The composition and specific chemical exergies of milk and its derivatives in ghee production plant are summarised in Table 7. The composition of raw milk consists of water, carbohydrate, fatty acids, protein and ash in form of lactose, glycerides, casein and salts respectively. The highest value specific chemical exergy was determined for ghee with 99.5% fat content i.e. 38427.66 kJ/kg, while skim milk (0.05% fat) was found to have lowest specific chemical exergy (1745.86 kJ/kg) content. Obviously increment in the fat content of the fluid would lead to the higher level of specific chemical exergy content which is attributed to higher chemical exergy of fat components compared to pure water.

610

G. Singh et al. / Energy 167 (2019) 602e618

Table 4 Exergetic Cost Rate Balance Equations for the units of Ghee Production Plant [45,46]. S.No

Component

Exergetic Cost rate Balance Equations for main units of Ghee Production Plant

Auxiliary Equations

1

Cream Storage Tank

C 1 þ C 12 þ C 22 þ Z T;CST ¼ C 2 þ C 13













c4 ¼ c27 c7 ¼ c28 c6 ¼ c7 c22 ¼ c23 ¼ c25 ¼ c26 c29 ¼ c30 ¼ c22 ¼ c23

































































2

Cream Supply Pump

C 2 þ C 23 þ Z T;CSP ¼ C 3

3

Butter Churner

C 3 þ C 24 þ C 22 þ Z T;BC ¼ C 4 þ C 27

4

Butter Melter



C 4 þ C 14 þ C 15 þ Z T;BM ¼ C 5 þ C 16 

5

Butter Supply Pump

C 5 þ C 25 þ Z T;BSP ¼ C 6

6

Ghee Boiler

C 6 þ C 26 þ C 17 þ Z T;GB ¼ C 7 þ C 28 þ C 18

7

Ghee Supply Pump

C 7 þ C 29 þ Z T;GSP ¼ C 8

8

Ghee Storage Tank











C 9 þ C 14 þ Z T;GST ¼ C 10 þ C 12 

9

Ghee Clarifier

C 9 þ C 30 þ Z T;GC ¼ C 10

10

Balance Tank

C 10 þ Z T;BT ¼ C 11







Table 5 The relation for Specific Heat and Density of Milk and Milk Derivatives [47]. Component

Specific Heat Capacity Equation

Density Equation

Protein

1:2089  T 1:3129  T 2  cp;protein ¼ 2:0082 þ 106 103 1:4733  T 4:808  T 2  cp;fat ¼ 21:9842 þ 106 103 1:9625  T 5:9399  T 2  cp;carbohydrate ¼ 1:5488 þ 106 103 1:8896  T 3:6817  T 2  cp;ash ¼ 1:0926 þ 106 103 9:0864  T 5:4731  T 2  cp;water ¼ 4:1762 þ 106 103

rprotein ¼ 2:0082  103 

Fat Carbohydrate Ash Water

5:184  T 10 4:1757  T rfat ¼ 9:2559  102  10 3:1046  T rcarbohydrate ¼ 1:5991  103  10 2:8063  T rash ¼ 2:4238  103  10 3:1439  T 3:7574  T 2 3 rwater ¼ 9:9718  10 þ  103 103

Table 6 The Composition of Milk and its Derivatives [47]. Constituents Whole Milk (3.79% MF) Skim Milk (0.05% MF) Composition Composition

Milk Cream (40% MF) Composition

Butter (81.11% MF) Composition

Buttermilk (3.28% MF) Composition

Ghee (Clarified Butter) (99.5% MF) Composition

Water Fat Carbohydrate Protein Ash

0.5465 0.4000 0.0285 0.0202 0.0048

0.1587 0.8111 0.0006 0.0085 0.0211

0.8810 0.0328 0.0474 0.0329 0.0059

0.0030 0.9950 0.0000 0.0015 0.0005

0.8790 0.0379 0.0457 0.0324 0.0078

0.9103 0.0005 0.0475 0.0336 0.0081

4.2. Thermodynamic analysis The energy analysis unveils the intriguing and non intriguing chapters of energy and cost conservation in a thermal system, while the exergy analysis captures the most prominent bottlenecks which crop up during the thermal processing of the fluids. The sustainable and non sustainable characteristics of the plant emerge from exergy conservation and degradation respectively. The exergetic appraisal of processing plant often eliminates the misrepresentation generated by energetic gauging of the subunits of the plant. On one side, where energy analysis create less productive picture of subunits of the plant, while on the other hand, exergy analysis provides ample illumination to the hidden potential of plant constituents. Consequently a rational and realistic technoeconomic picture is portrayed by exergoeconomic analysis of the plant. The type of fluid and its state parameters such as pressure, temperature and mass flow rates for the streams of milk are given in Table 8 based on their state numbers displayed in Fig. 1. With the help of data shown in the Table 8, thermodynamic derivatives were computed for each of the subunits of dairy

processing plant (Table 9 and Table 10). A little focus upon the energy and exergy chart would provide us information on estimation of energy and exergy efficiency of ghee plant, which was enumerated as 70.08% and 34.21% respectively (Tables 9 and 10). The low magnitudes of the above specified derivatives gave us insight about the poor performance and remunerative returns of the plant. The deficiencies in the technological features of subunits of the plant portrayed less productive behaviour of ghee production plant. The energy efficiencies of butter churner, butter melter and ghee boiler were diagnosed to be 22.88%, 66.71% and 60.05% respectively whereas its exergy counterparts were recognised to be 1.03%, 21.48% and 38.43% respectively (Fig. 2). The least values of exergy efficiencies were estimated for butter churner (1.03%) after the centrifugal pumps (0.67%) as the same consumed substantial amount of electrical energy for the purpose of conversion of cream fluid to butter and fluid pumping respectively. As far as energy and exergy efficiency of individual units were concerned, the electrical energy consuming elements of the plant recorded much less magnitude compared to its thermal

G. Singh et al. / Energy 167 (2019) 602e618

611

Table 7 Compositions and standard specific chemical exergy of milk constituents [47]. Sr. Component No.

Standard Chemical Exergy (kJ/mol)

g/kg of 0.05% Fat g/kg of 3.8% Fat Skim Milk Whole Milk

g/kg of 3.28% Fat g/kg of 40% Fat Butter Milk Milk Cream

g/kg of 81.11% Fat g/kg of 99.50% Fat Ghee White Butter (Clarified Butter)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

9.500E-01 5.988Eþ03 2.320Eþ03 3.626Eþ03 4.931Eþ03 6.237Eþ03 7.543Eþ03 8.848Eþ03 9.501Eþ03 1.015Eþ04 1.081Eþ04 1.146Eþ04 1.277Eþ04 6.020Eþ03 8.631Eþ03 9.937Eþ03 1.059Eþ04 1.124Eþ04 1.102Eþ04 1.081Eþ04 9.937Eþ03 1.124Eþ04 1.102Eþ04 1.102Eþ04 5.837Eþ05 6.145Eþ05 6.176Eþ05 4.832Eþ05 4.734Eþ05 3.585Eþ05 1.691Eþ06 4.113Eþ06 3.832Eþ06 1.025Eþ07 2.555Eþ07 1.906Eþ06 5.621Eþ05 1.970Eþ01 1.460Eþ01 4.040Eþ01 5.100Eþ00

9.103Eþ02 4.750Eþ01 2.200E-02 1.200E-02 7.010E-03 1.350E-02 1.650E-02 5.460E-02 4.500E-03 1.530E-01 2.000E-03 6.110E-02 1.000E-03 1.500E-03 4.000E-03 5.010E-03 5.010E-04 1.140E-01 8.010E-03 3.500E-03 2.000E-03 1.050E-02 1.000E-03 2.000E-03 1.036Eþ01 2.690Eþ00 1.057Eþ01 3.420Eþ00 3.310Eþ00 1.240Eþ00 4.140E-01 5.180E-01 5.180E-02 1.030E-02 9.330E-02 5.180E-02 8.290E-01 2.540Eþ00 2.820Eþ00 9.840E-01 1.710Eþ00 1743.85

8.810Eþ02 4.740Eþ01 1.429Eþ00 7.873E-01 4.681E-01 8.848E-01 1.075Eþ00 3.583Eþ00 2.924E-01 1.005Eþ01 1.283E-01 4.010Eþ00 6.778E-02 9.746E-02 2.614E-01 3.285E-01 3.205E-02 7.489Eþ00 5.242E-01 2.293E-01 1.313E-01 6.899E-01 6.533E-02 1.312E-01 1.015Eþ01 2.638Eþ00 1.035Eþ01 3.347Eþ00 3.245Eþ00 1.220Eþ00 4.243E-01 5.214E-01 5.096E-02 3.070E-02 9.094E-02 5.073E-02 8.086E-01 2.459Eþ00 2.731Eþ00 9.463E-01 1.658Eþ00 2978.58

1.587Eþ02 6.000E-01 3.534Eþ01 1.947Eþ01 1.158Eþ01 2.188Eþ01 2.658Eþ01 8.860Eþ01 7.232Eþ00 2.486Eþ02 3.174Eþ00 9.916Eþ01 1.676Eþ00 2.410Eþ00 6.465Eþ00 8.124Eþ00 7.926E-01 1.852Eþ02 1.296Eþ01 5.671Eþ00 3.246Eþ00 1.706Eþ01 1.615Eþ00 3.244Eþ00 2.621E-02 6.816E-03 2.674E-02 8.647E-03 8.385E-03 3.152E-03 1.096E-03 1.347E-03 1.317E-04 7.931E-05 2.350E-04 1.311E-04 2.089E-03 6.653E-02 7.389E-02 2.560E-02 4.485E-02 31087.04

Water Lactose Butyric Caproic Caprylic Capric Lauric Myristic Pentadecylic Palmitic Margaric Stearic Arachidic Caproleic Myristoleic Palmitoleic Heptadecenoic Oleic Linoleic Linolenic Trans Palmitoleic acid Vaccenic acid Linoelaidic acid Conjugated linoleic acid as1-casein as2-casein b-casein k-Casein b-Lactoglobulin a-Lactalbumin Serum albumin Immunoglobulin G1 Immunoglobulin G2 Immunoglobulin A Immunoglobulin M Lactoferrin (LF) Proteose-peptone Calcium chloride Potassium chloride Magnesium chloride Sodium chloride Total Specific Chemical Exergy (kJ/kg)

8.790Eþ02 4.570Eþ01 1.655Eþ00 9.122E-01 5.423E-01 1.025Eþ00 1.245Eþ00 4.151Eþ00 3.388E-01 1.165Eþ01 1.487E-01 4.646Eþ00 7.852E-02 1.129E-01 3.029E-01 3.806E-01 3.713E-02 8.676Eþ00 6.073E-01 2.657E-01 1.521E-01 7.992E-01 7.569E-02 1.520E-01 9.992Eþ00 2.598Eþ00 1.019Eþ01 3.296Eþ00 3.196Eþ00 1.201Eþ00 4.179E-01 5.135E-01 5.018E-02 3.023E-02 8.956E-02 4.996E-02 7.963E-01 2.459Eþ00 2.731Eþ00 9.463E-01 1.658Eþ00 3101.76

5.465Eþ02 2.851Eþ01 1.763Eþ01 9.620Eþ00 5.610Eþ00 1.085Eþ01 1.322Eþ01 4.370Eþ01 3.610Eþ00 1.227Eþ02 1.600Eþ00 4.890Eþ01 8.010E-01 1.200Eþ00 3.210Eþ00 4.010Eþ00 4.010E-01 9.139Eþ01 6.410Eþ00 2.800Eþ00 1.600Eþ00 8.420Eþ00 8.010E-01 1.600Eþ00 6.220Eþ00 1.620Eþ00 6.350Eþ00 2.050Eþ00 1.990Eþ00 7.510E-01 2.500E-01 3.110E-01 3.100E-02 6.200E-03 5.600E-02 3.100E-02 4.900E-01 1.520Eþ00 1.690Eþ00 5.910E-01 1.030Eþ00 16439.49

8.835Eþ02 4.611Eþ01 1.320Eþ00 7.200E-01 4.210E-01 8.100E-01 9.500E-01 3.280Eþ00 2.600E-01 9.200Eþ00 1.100E-01 3.670Eþ00 6.130E-02 9.210E-02 2.410E-01 3.010E-01 3.120E-02 6.850Eþ00 4.810E-01 2.100E-01 1.200E-01 6.300E-01 6.010E-02 1.200E-01 1.006Eþ01 2.620Eþ00 1.026Eþ01 3.320Eþ00 3.220Eþ00 1.210Eþ00 4.020E-01 5.030E-01 5.120E-02 1.120E-01 9.100E-02 5.010E-02 8.010E-01 2.470Eþ00 2.740Eþ00 9.210E-01 1.660Eþ00 38427.66

Table 8 List of energy and exergy values at all state points of ghee production plant. 

S.NO

STATE

T (K)

P (bar)

mðkg=sÞ

Exergy (kW)

Energy (kW)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 27 28

40% F CREAM 40% F CREAM 40% F CREAM 81.11% F BUTTER 81.11% F BUTTER 81.11% F BUTTER 99.5% F GHEE 99.5% F GHEE 99.5% F GHEE 99.5% F GHEE 99.5% F GHEE CHILLED WATER COLD WATER STEAM WATER CONDENSATE STEAM CONDENSATE STEAM WATER CONDENSATE 3.28%F BUTTERMILK WATER VAPOUR

281.15 278.15 278.15 288.15 368.15 368.15 383.15 383.15 348.15 348.15 348.15 274.65 276.65 404.45 298.15 308.15 406.67 388.15 393.36 298.15 301.15 288.15 383.15

1.25 1 2 1 1 2 1 2 1.5 1.25 1 2.5 1.5 2.81 1.5 1.25 3 1.25 2 1.5 1 1 1

0.144 0.144 0.144 0.119 0.119 0.119 0.101 0.101 0.101 0.101 0.101 0.0834 0.0834 0.013 0.152 0.165 0.052 0.052 0.0022 0.832 0.834 0.025 0.018

0.25 0.34 0.35 0.04 1.79 1.80 1.73 1.74 0.64 0.64 0.64 0.35 0.29 8.84 0.01 0.12 35.64 12.85 1.42 0.04 0.050.02 0.34

8.18 9.62 9.62 2.51 17.57 17.57 14.35 14.35 8.44 8.44 8.44 8.20 7.50 34.20 0.00 6.90 136.93 75.89 5.76 0.00 10.47 0.95 2.85

612

G. Singh et al. / Energy 167 (2019) 602e618

Table 9 Energy analysis of all components of ghee production plant. S.NO

ITEM

Ein (kW)

Eout (kW)

EL (kW)

h (%)

EIP (kW)

Eb,

1 2 3 4 5 6 7 8 9 10

STORAGE TANK PUMP-1 BUTTER CHURNER BUTTER MELTER PUMP-2 GHEE BOILER PUMP-3 STORAGE TANK GHEE CLARIFIER BALANCE TANK

17.13 11.12 15.12 36.71 19.08 155.01 15.85 20.11 8.94 8.44

17.12 9.62 3.46 24.49 17.58 93.09 14.35 18.91 8.44 8.44

0.01 1.5 11.66 12.22 1.5 61.92 1.5 1.2 0.5 0

99.94 86.51 22.88 66.71 92.14 60.05 90.54 94.03 94.41 100.00

0.00 0.20 8.99 4.07 0.12 24.73 0.14 0.07 0.03 0.00

0.01 1.63 12.67 13.28 1.63 67.30 1.63 1.30 0.54 0.00

k

EF,k 5.57 3.62 4.92 11.94 6.20 50.41 5.15 6.54 2.91 2.74

Table 10 Exergy Analysis of all components of Ghee Production Plant. S.NO

ITEM

Exin (kW)

Exout (kW)

ExD (kW)

J (%)

ExIP(kW)

Exb,k (%)

ExF,k (%)

SIk

1 2 3 4 5 6 7 8 9 10

STORAGE TANK PUMP-1 BUTTER CHURNER BUTTER MELTER PUMP-2 GHEE BOILER PUMP-3 STORAGE TANK GHEE CLARIFIER BALANCE TANK

1.35 1.84 5.85 8.89 3.29 37.94 3.2 3.2 1.14 0.64

0.63 0.35 0.06 1.91 1.8 14.58 1.74 0.69 0.64 0.64

0.72 1.49 5.79 6.98 1.49 23.36 1.46 2.51 0.5 0

46.67 0.66 1.03 21.48 0.66 38.43 0.66 21.56 56.14 100.00

0.38 1.48 5.73 5.48 1.48 14.38 1.45 1.97 0.22 0.00

1.63 3.36 13.07 15.76 3.36 52.73 3.30 5.67 1.13 0.00

2.00 2.73 8.69 13.20 4.89 56.34 4.75 4.75 1.69 0.95

1.88 1.01 1.01 1.27 1.01 1.62 1.01 1.27 2.28 1.00

120 100

100.00

99.94 94.03

92.14

100.00

94.41

90.54

86.51

80 66.71 60.05

60

56.14 46.67

Energy Efficiency (%)

38.43

40 22.88

Exergy Efficiency (%) 21.56

21.48

20 0.66

1.03

0.66

0.66

0

Fig. 2. Comparative Analysis of Energy and Exergy Efficiency for each subunits of Ghee Production Plant.

energy counterparts. Amongst the units involved with thermal energy consumption, the exergy efficiency of cream storage unit was measured up to be highest i.e. 46.67%, followed by ghee boiler (38.43%) and ghee storage tank (21.56%). The specific energy and exergy destruction figures for the entire plant were calculated as 911 kJ/kg and 438.61/kg respectively (Tables 9 and 10). The destruction of cool exergy [18] in the cream storage tank was ascribed to rapid rate of cooling, primarily required for achievement of effective cream ripening or instantaneous crystallization of milk fat and optimum yield of butter content. The structural integrity or mechanical strength of milk fat is primarily obtained by expeditious chilling activity accompanied by non violent agitation of milk fat in cream storage tank. The initiation of high degree of partial coalescence among milk fat globules or establishment of Van der Waal’s forces of attraction between the

liquid and solid phases of milk fat, is realised at the cost of sufficient amount of cool exergy destruction i.e. 5 kJ/kg of pasteurised cream. The amount of exergy destruction in the butter churner equipment is mainly influenced by fat content of cream, cream feed temperature, and shear rate of baffle/beater or rotational speed of butter churner. The high shearing effect has direct impact upon globule structure, i.e. destruction of Van der Waal’s force of attraction existing amongst the milk fat globules causes huge fat loss with the butter milk [49]. The operation of aforementioned factors under controlled regime will materialise phase inversion of milk cream with desirable fat content, whereby the fat globule membranes are disrupted, globule coalesce and oil leaks out from the continuous phase of milk fat composition. The butter quality often gets deteriorated under low churning speed, in order to overcome the same difficulty, the optimum operational speed of

G. Singh et al. / Energy 167 (2019) 602e618

butter churner is in the range of 45e60 rpm [2]. The vigorous agitation inside the butter churning equipment creates pressure upon fat globules owing to severe shearing action; which causes destabilisation of emulsion. The process of frequent collisions amongst the fat globule is always accompanied by excessive amount of exergy destruction; the magnitude of which for the present case is estimated as 40.21 kJ/kg of pasteurised cream. Further, multiphase emulsion of milk fat suddenly experiences a rise in viscosity after churning activity; caused by irregular aggregation of butter grains which exists as three dimensional crystal networks [50] in continuous phases of milk fat composition. In the butter melting unit, the thermal and electrical energies are consumed in melting of heterogeneous fatty acid composition, primarily composed of glycerides, as well as in uniform distribution or penetration of heat into continuous phases of solid and liquid milk fat with aqueous droplets dispersed in it, respectively. After weighing upon the exergetic performance of key units, it was found that highest level of irreversibility was determined for ghee boiler i.e. 380.50 kJ/kg of ghee production (Fig. 3). The production activity of clarified butter from the butter required severe heat treatment along with regular agitations of the liquid fluid in the ghee boiler. The value of Prandtl Number for the butter is more than two times higher than that of cream fluid; consequently, the thermal diffusivity of butter is comparatively lower than that of its cream counterpart. Hence, high degree of thermal treatment assisted by regular agitation is required for deeper penetration of thermal energy content into the continuous phase of liquid fat content so that necessary latent heat content could be made available for complete removal of aqueous content dispersed inside it. The aforementioned process is always accompanied by high temperature gradient owing to large difference in temperature of steam and liquid butter content which could be adjudged as the key reason for highest amount of exergy degradation in the ghee boiler. In case of ghee clarifier, the electrical energy was consumed i.e. 4.95 kJ/kg of ghee, in removal of high density solid impurities present in the clarified butter fat, with the help of centrifugal action, in such a manner that sedimentation of solids assisted by disk stack arrangement settle towards the outer periphery of centrifugal clarifier. The joint contribution of butter churner, butter melter and ghee boiler towards total energy and exergy destruction was 92.48% and 81.56% respectively. Therefore, it could be understood that the

613

contribution made by pumping and storage unit towards the same was comparatively very small i.e. 18.44%. It is worth pointing out that the electrical energy consumption of the pumping systems in dairy processing plants can be markedly lowered using the variable speed drive (VSD) controller. The combined share of butter churner and melter towards total energy and exergy destruction was ascertained to be 25.95% and 28.53% respectively. However, a major chunk of exergy destruction had come from ghee boiler (52.96%); the energy counterpart of which was calculated as 67.30%. The energy destruction in the ghee boiler was 5.31 and 5.07 times to that of butter churner and butter melter respectively. The magnitude of irreversibilities in case of butter melter and ghee storage tank was ascertained to be nearly equal in values i.e. 21.48% and 21.56% respectively. Despite the higher level of agitations of cream in butter churner, the level of irreversibility in the cream processing section was far lower in magnitude than that of butter processing section which could be ascribed to the fact that heat and mass transfer in the butter processing section occurred at elevated temperature in comparison to cream processing section. Thus, the role of thermal energy degradation was far more pronounced than that of electrical energy consumption. The specific energy and exergy improvement potential of the entire plant was computed to be 379.80 kJ/kg and 322.57 kJ/kg respectively. The highest value of energy and exergy improvement potential was associated with ghee boiler followed by butter churner and butter melter (Tables 9 and 10). The combined share of butter churner and butter melter towards exergy improvement potential was notified to be 34.41%. The energy and exergy improvement potential for the entire plant was determined to be 41.69% and 73.94% of its total destructive counterpart. The butter churner and melter had reported almost same value of exergy improvement potentials whereas the energy derivative of former was more than two times to that of latter. The combined value of exergy improvement potential and exergy destruction for pumping and storage units of the plant were calculated to be 5.01 kW and 7.17 kW respectively. There was approximately a difference of 10.5 kW between exergy destructions and exergy improvements of butter processing section. The relative energy and exergy destruction ratio were found out to be highest for the ghee boiler i.e. 67.30% and 52.73% respectively (Fig. 4). Similarly, the energetic and exergetic factor of the ghee boiler

70 61.92

60 50 40 30

Energy Loss (kW)

23.36

Exergy Destruction (kW)

20 11.66

10 0

5.79 0.010.72

1.501.49

12.22 6.98 1.501.49

1.501.46

2.51 1.20

0.500.50

0.000.00

Fig. 3. Comparative Analysis of Energy and Exergy Destruction for each subunits of Ghee Production Plant.

614

G. Singh et al. / Energy 167 (2019) 602e618

showed similar trend i.e. 50.41% and 56.34% respectively. The sustainability index of cream storage tank (SI: 1.88) was second highest after ghee clarifier (SI: 2.28) while the value of sustainability index for the ghee boiler and butter melter were reported as 1.62 and 1.27 respectively (Table 10). From the Table 10; it was quite evident that the sustainability index of the entire ghee production plant was quite low as the amount of exergy destruction for 1 kg of ghee production was substantially high i.e. 438.61 kW and the same was discovered as a main reason behind low productivity of the plant. Further, the complete absence of heat integration amongst key units of plant such as ghee boiler, ghee storage tank and butter melter resulted into excessive thermal energy destruction vis a vis its electrical energy counterpart. The overall picture of resource consumption for the ghee production plant was prominently occupied by thermal energy i.e. 73.48% (Fig. 5), while rest of the energy requirement was fulfilled by electrical energy counterpart. 4.3. Thermo-economic analysis The thermo-economic technique was instituted for better understanding of impact of thermal and economic variables or constraints upon the overall performance of the system. The laws of thermodynamics are integrated with economic limitations in order to develop linear set of thermo-economic equations, which upon its solution would produce a rational picture of exergetic destruction or losses along with their monetary quantification. The insightful information about the hidden potentials and deficiencies of a plant are better communicated by Specific Exergy Costing Method (SPECO). The solution of linear set of exergoeconomic equation produced cost flow rates and that too in close interrelation with exergetic input or output at all the state points of the system, uncovers the role of each constituting element of the plant in terms of key indices such as percentage relative cost difference (PRCD), cost rate of exergy demolition, exergoeconomic factor, exergetic cost, cost per unit exergy and specific manufacturing cost of the material being processed.

Specific Exergy Consumption (%)

26.52%

Electrical Energy Thermal Energy

73.48%

Fig. 5. Percentile contribution of energy to the specific exergy consumption of Ghee Production Plant.

The gravity of total cost rate of exergy destruction could be weighed up in terms of the fact that higher the magnitude of it, greater will be the impact of a subunit on the characteristcis or behaviour of overall system. Hence, by restructuring the order of performance of each constituent of the plant on the basis of SPECO background, the vital information pertaining to upgradation of plants’ performance is synthesized and processes. The Table 11 displayed the condensed form of thermo-economic output in terms of aforementioned indices. Thus, from the Table 11, it was elucidated that total levelised cost rate of ghee production plant was calculated to be 129.73 R/H. The maximum and minimum values of levelised cost rate was associated with butter churner (75.12 R/H) and feed pumps (2.03 R/H) respectively. The key subunits of plant such as butter churner, butter melter, ghee boiler and ghee clarifier had consumed 77.44% share of total levelised cost rate. Similarly, the combined value of levelised cost rate for the all pumping units as well as storage cum balance tanks was computed to be 19.06 R/H. The levelised cost of cream storage tanks

80 70

67.30

60 52.73

Relative Energy Destruction ratio (%)

50 40

Relative Exergy Destruction Ratio (%)

30 20

15.76 12.6713.07

13.28

10 0

5.67 0.01

1.63

1.63

3.36

1.63

3.36

1.63

3.30 1.30

0.54 1.13

0.00 0.00

Fig. 4. Comparative analysis of relative energy and exergy destruction ratio for ghee production plant.

G. Singh et al. / Energy 167 (2019) 602e618

615

Table 11 Cost Rates associated with first capital investment and O&M costs for subcomponents of the Ghee Production Plant. 







S.NO

ITEM

PEC (R)

Z CI;k (R/H)

Z OM;k (R/H)

Z T;k (R/H)

D D;k (R/H)

rk (%)

fk (%)

TOCRk (R/H)

1 2 3 4 5 6 7 8 9 10

STORAGE TANK PUMP-1 BUTTER CHURNER BUTTER MELTER PUMP-2 GHEE BOILER PUMP-3 STORAGE TANK GHEE CLARIFIER BALANCE TANK

90000 18000 666000 95000 18000 125000 18000 25000 75000 20000

7.63 1.53 56.48 8.06 1.53 10.60 1.53 2.12 6.36 1.70

2.52 0.50 18.64 2.66 0.50 3.50 0.50 0.70 2.10 0.56

10.15 2.03 75.12 10.72 2.03 14.10 2.03 2.82 8.46 2.26

108.55 209.04 863.78 341.07 81.00 1275.52 82.18 228.22 81.32 0.00

2.79 2.70 96.73 97.29 1.05 45.36 2.85 63.99 6.38 2.43

8.55 0.96 8.00 3.05 2.45 1.09 2.42 1.22 9.42 100.00

118.70 211.07 938.89 351.79 83.03 1289.62 84.21 231.04 89.78 2.26

was nearly 3.6 times higher than its ghee counterpart as high capacity tank was required to store the pasteurised cream. The material processing was found to be highly expensive in the butter melter (97.29%) followed by butter churner (96.73%), ghee storage tank (63.99%) and ghee boiler (45.36%). The fluid processing cost in ghee storage tank was far higher than that of its cream processing counterpart (Fig. 6). The range of variation of PRCD value for the pumps was reported as 1.05e2.85%. The PRCD value for the ghee clarifier was significantly higher than other electrical energy consuming units of the plant and computed as 6.38%. The material processing cost of butter melter and butter churner was estimated to be more than two times higher than that of ghee boiler. The substantially high value of exergoeconomic factor for ghee clarifier (9.42%), storage tank (8.55%) and butter churner (8.00%) designated the dominance of capital investment over degree of thermodynamic degradation where as the prominence of latter was truthfully concluded for subunits such as ghee boiler (1.09%), ghee storage tank (1.22%) and all the three pumps (Table 11). Quite intriguingly, it was noticed that although the exergoeconomic factor for the cream storage tank and butter churner was more or less close to each other, however the former was influenced more

by investment factor while the latter registered higher preeminence of thermal degeneracy. The study has divulged that percentage relative cost difference was directly proportional to cost rate of exergy degradation (CRED) i.e. for all the subunits which have low values of PRCD, their CRED values were also of low magnitudes and vice versa. The total operating cost rate for ghee boiler was almost 37.36% higher than butter churner while contrary to aforementioned conclusion; the PRCD value for butter churner was more than two times higher than its ghee boiler counterpart which clearly elucidated that the repercussions of thermodynamic losses was far more discernible in the latter case. The total operating cost rate was found to be highest for ghee boiler i.e. 1289.62 R/H followed by butter churner (938.89 R/H) and butter melter (351.79 R/H) respectively (Fig. 7). The pumping sets and storage units together comprised 21.40% of TOCR while there was a difference of less than 1% in TOCR for two of them. The main subunits of the plant e.g. butter churner, ghee boiler and butter melter consumed 75.88% share of total cost composition matrix. Amongst the key electrical energy consuming units of the plant; the maximum value of total operating cost rate was reported for cream supply pump (211.07 R/H) followed by ghee clarifier

Percentage Relative Cost Difference (r%)

BALANCE TANK

2.43

GHEE CLARIFIER

6.38

STORAGE TANK

63.99

PUMP-3

2.85

GHEE BOILER

45.36

PUMP-2

1.05

BUTTER MELTER

97.29

BUTTER CHURNER

96.73

PUMP-1

2.70

STORAGE TANK

2.79

0

20

40

60

80

Fig. 6. Percentage Relative Cost Difference of each component of Ghee Production Plant.

100

120

616

G. Singh et al. / Energy 167 (2019) 602e618

Total Operating Cost Rate (R/H) BALANCE TANK

2.26

GHEE CLARIFIER

89.78

STORAGE TANK

231.04

PUMP-3

84.21

GHEE BOILER

1289.62

PUMP-2

83.03

BUTTER MELTER

351.79

BUTTER CHURNER

938.89

PUMP-1

211.07

STORAGE TANK

118.70

0

200

400

600

800

1000

1200

1400

Fig. 7. Total Operating Cost Rate for each subunit of Ghee Production Plant.

(89.78 R/H) and ghee supply pump (84.21 R/H). It was quite interesting to note that consumption of thermal resources for the ghee storage tank was probed to be nearly two and three times of ghee storage tank and butter melter respectively, which showed that energy consumption in chilling activity was lower than its heating counterpart. The aforementioned statement was supported by respective PRCD values and exergoeconomic indices i.e. higher thermal degradation was reported for ghee storage tank while its lower counterpart was associated with cream storage tank. The thermal deteriorations were sounded most prominent in butter melter and ghee boiler, the clear reflection which was made by their respective thermo-economic indices. Despite the higher value of TOCR for ghee boiler, the fluid processing cost linked with it; was not that significant as it was with units such as butter churner and butter melter, as the consumption of high grade energy in the former was comparatively cheaper than that of thermal energy counterpart in the latter. The aforementioned conclusion was quite perfectly endorsed by their respective exergoeconomic factors. 4.4. Thermal refinement of plant by heat recovery The present architecture of the ghee production plant could be suitably modified to exploit the available thermal energy potential associated with ghee boiler. As part of innovation, the thermal energy associated with molten ghee as well as condensate, coming out from the ghee boiler, could be fruitfully used in heating the butter in butter melter to the required temperature of 368.15 K. The proposed conceptual change in the configuration of plant is reflected in Fig. 8. The clarified butter (ghee) in molten state is passed through ghee clarifier to remove crud or sludge present in the ghee so that presence of crud must not corrode or block the pipelines. Further, ghee as well as condensate coming out from the ghee boiler is passed through butter melter with some additional retrofitting (piping arrangement) so as to make use of thermal energy potential associated with both the entities. In the final stage, the ghee coming out from the butter melter is directly sent for packing via balance tank. The major outcomes of the proposed conceptual configuration are tabulated below in Table 12. In the light of current scenario of ghee production and consumption in Indian Subcontinent, the appropriate modifications or

Fig. 8. Concept of heat recovery in ghee production plant.

retrofitting in ghee production unit could assist in achievement of higher production rates at the current level of resource consumption. Further, it is quite feasible to design and develop solar or biomass energy assisted scraped surface heat exchanger for ghee production activity, which would be a big breakthrough in reducing dependence upon fossil fuel consumption. Overall, exergy and exergoeconomic concept of system evaluation offer a strong substitute to many techniques available in literature in identification of possible exergetic improvements in plant; on the basis of which, major exergy and economic savings could be ascertained. In the line of same, methods such as pinch analysis, exergoeconomic optimization, life cycle assessment and exergoenvironmental analysis could help in preparation of sensible perception about operational costs as well as in measurement of environmental impact of complex energy system. 4.5. Uncertainty analysis The magnitudes of total uncertainty for the main variables of ghee production plant are given in Table 13. The consequences intimated that uncertainties associated all the thermal parameters were well within the reasonable range (<5%).

G. Singh et al. / Energy 167 (2019) 602e618

617

Table 12 Major advantages of the proposed configuration in Ghee Production Plant. S.No

Technical Parameter

Existing Configuration

Proposed Configuration

Change in Value (%)

1 2 3 4 5 6 7 8

Universal Exergy Efficiency of Plant (%) Overall Exergy Destruction (kW) Overall Sustainability Index Exergy Efficiency of Butter Melter (%) Sustainability Index of Butter Melter Overall Steam Consumption (kg/h) Cost Rate of Exergy Destruction (R/h) Specific Manufacturing Cost of Ghee Production (R/kg)

34.21% 44.30 1.52 21.38% 1.27 241.92 3270.68 9.35

38.47% 36.01 1.63 63.30% 2.73 187.20 2765.54 7.96

4.26% (↑) 18.71% (↓) 7.24% (↑) 41.92% (↑) Doubles 29.23% (↓) 15.44% (↓) 14.86% (↓)

Table 13 The Uncertainty analysis for technical parameters of Ghee Production Plant [25]. S.No

Parameter

1 2 3 4 5 6 7 8 9 10 11

Uncertainty Uncertainty Uncertainty Uncertainty Uncertainty Uncertainty Uncertainty Uncertainty Uncertainty Uncertainty Uncertainty

Total Uncertainty in in in in in in in in in in in

Cream Temperature Measurement Cream Pressure Measurement Cream Mass Flow Rate Measurement Butter Temperature Measurement Butter Pressure Measurement Butter Mass Flow Rate Measurement Ghee Temperature Measurement Ghee Pressure Measurement Ghee Mass Flow Rate Measurement Steam Mass Flow Rate Measurement Steam Pressure Measurement

±1:8027 ±0:3605 ±0:0215 ±3:7527 ±0:4123 ±0:0067 ±2:8206 ±:0347 ±0:1182 ±0:0037 ±0:0284

5. Conclusions In order to achieve thermodynamic perfection, it was quite imperative to secure a blend of optimum values for all the thermal and economic variables so that exergetic and exergoeconomic fertility could be magnified. The necessary improvements in constructional features of constituents of the plant could assist in realisation of thermo-economic prosperity of the plant. The cost rationalisations as well as better quantification of thermodynamic framework were identified as key essentials for upliftment of overall performance of the ghee production plant. The overall energy efficiency and universal exergy efficiency of ghee production plant were diagnosed to be 70.04% and 34.21% respectively. The specific energy and exergy destruction of ghee production plant were recognised as 911 kJ/kg and 438.61 kJ/kg respectively. The specific energy and exergy improvement potential of ghee production plant were ascertained to be 379.80 kJ/kg and 322.57 kJ/kg respectively. The highest value of specific energy and exergy destruction was calculated for ghee boiler i.e. 613.07 kJ/kg and 231.29 kJ/kg respectively. The highest fluid processing cost or percentage relative cost difference was associated with butter melter (97.29%) followed by butter churner (96.73%) and ghee storage tank (63.99%) respectively. The total operating cost rate for the ghee production plant was computed to be 3400.41 R/H, which is the summation of cost rate of exergy destruction, levelised cost rate of capital investment and levelised cost rate of operation and maintenance cost. Further, the maximum contribution towards total operating cost rate was given by ghee boiler (37.92%) followed by butter churner (938.89 R/H) and butter melter (351.79 R/H). The highest value of exergoeconomic factor was calculated for ghee clarifier (9.42%) followed by cream storage tank (8.55%) and butter churner (8%) which magnified the role of capital investment towards total cost composition of the plant. Similarly, the magnitude of exergoeconomic factor for ghee boiler (1.09%) and butter melter (3.05%) reflected that the exergetic degradations were of

important consequences. In proposed conceptual configuration of the ghee production plant, the thermal energy potential available with ghee boiler, could be fruitfully exploited by suitably retrofitting it with butter melter, so as to achieve an increment of 4.26% in universal exergy efficiency with simultaneous decrement in magnitudes of overall exergy destruction, overall steam consumption and cost rate of exergy destruction i.e. 18.71%, 29.23% and 15.44% respectively; thereby having significant improvement in sustainability characteristics of butter melter as well as that of complete ghee production plant. Further, in the existing configuration of ghee production plant, exergetic cost and cost per unit exergy of the plant were calculated to be 113.53 R/H and 49.46 R/MJ respectively. In view of optimum performance of the ghee production plant; it was highly imperative to secure equilibrium among thermal and economic variables of the all constituents of the plant so that specific manufacturing cost of ghee production could be minimised; which in the present case was enumerated as 9.35 R/H; and by exercising the heat recovery option, the latter would register a decrement of 14.86% in its magnitude. Acknowledgement The author would like to acknowledge the assistance given by National Dairy Research Institute Karnal, Haryana (India) and greatly appreciate the cooperation of technical staff and management of Dairy Plant throughout plant assessment phase. References [1] Juriaanse AC, Heertje I. Microstructure of shortenings, margarine and butter a review. Food Struct 1988;07(2):181e8. https://digitalcommons.usu.edu/ foodmicrostructure/vol7/iss2/8. [2] Kalla Adarsh M. Development and performance evaluation of frustum cone shaped butter churn. Master Thesis. Chhattisgarh, India: College of Dairy Science and Food Technology; 2014. [3] Kumar M, Pandya HB, Dodiya KK, Bhatt R, Mangukiya M. Advancement in industrial methods of ghee making process at Sarvottam Dairy, Bhavnagar, Gujrat, India. Int J Sci Environ Technol 2017;06(03):1727e36. [4] Joshi R.M. India’s Dairy Export: opportunities, challenges and strategies IIFA 2015; National Seminar, New Delhi, India. [5] Indian dairy industry: current status, challenges and issues under WTO regime. 2015. http://wtocentre.iift.ac.in/workingpaper/dairy.pdf [Accessed 27 December, 2017]. [6] Statista. The statistics portal UK. 2018. https://www.statista.com [Accessed 14 May, 2018]. [7] Outlook Food. Biannual report of global food markets. 2017. http://www.fao. org/3/a-i7343e.pdf [Accessed 27 December 2017]. [8] Dairy industry vision 2030 “ reimaging indian industry”. 2014. https://www. suruchiconsultants.com/pageDownloads/report/63_Surchi_DIV_2030.pdf [Accessed 27 December, 2017]. [9] India’s dairy sector: structure, performance, and prospects. 2017. https:// www.ers.usda.gov/webdocs/publications/82639/ldpm-272-01.pdf?v¼42800 [Accessed 27 December, 2017]. [10] Zisopoulos FK, Rossier-Miranda FJ, Goot AJV, Boom RM. The use of exergetic indicators in the food industryeA review. Crit Rev Food Sci Nutr 2017;57: 197e211. https://doi.org/10.1080/10408398.2014.975335.s.

618

G. Singh et al. / Energy 167 (2019) 602e618

[11] Taner T. Optimisation processes of energy efficiency for a drying plant: a case of study for Turkey. Appl Therm Eng 2015;80:247e60. https://doi.org/ 10.1016/j.applthermaleng. 2015.01.076. (2015). [12] Taner T. Energy and exergy analyze of PEM fuel cell: a case study of modelling and simulations. Energy 2018;143:284e94. https://doi.org/10.1016/ j.energy.2017.10.102. [13] Topal H, Taner T, Altinci Y, Amirabedin E. Application of Tri-generation with direct co-combustion of poultry waste and coal: a case study in the poultry industry from Turkey. Therm Sci 2017. https://doi.org/10.2298/ TSCI170210137T. [14] Topal H, Taner T, Naqvi SAH, Altinsoy Y, Amirabedin E, Ozkeymak M. Exergy analysis of a circulating fluidized bed power plant co-firing with olive pits: a case study of power plant in Turkey. Energy 2017;140:40e6. https://doi.org/ 10.1016/j.energy.2017.08.042. [15] Taner T. Thermoeconomic analysis for the power plants of sugar factories. J Faculty Eng Arch Gazi Univ 2014;29(2):407e14. [16] Sorgüven E, Ozilgen M. Energy utilization, carbon dioxide emission, and exergy loss in the flavoured yogurt production process. Energy 2012;40(1): 214e25. https://doi.org/10.1016/j.energy.2012.02.003. [17] Waheed MA, Jekayinfa SO, Ojediran JO, Imeokparia OE. Energetic analysis of fruit juice processing operations in Nigeria. Energy 2008;33(1):35e45. https://doi.org/10.1016/j.energy.2007.09.001. [18] Dowlati M, Mojarab Soufiyan M, Aghbashlo M. Exergetic performance analysis of an Ice-Cream manufacturing plant: a comprehensive survey. Energy 2017;123:445e59. https://doi.org/10.1016/j.energy.2017.02.007. [19] Mojarab Soufiyan, Aghbashlo M. Application of exergy analysis to the dairy industry: a case study of yogurt drinks production plant. Food Bioprod Process 2017;101:118e31. https://doi.org/10.1016/j.fbp.2016.10.008. [20] Nasiri F, Aghbashlo M, Rafiee S. Exergy analysis of an industrial-scale ultrafiltrated (UF) cheese production plant: a detailed survey. Heat Mass Tran 2017;53(2):407e24. https://doi.org/10.1007/s00231-016-1824-3. [21] Goot AJV, Pelgrom PJM, Berghout JAM, Geetrs MEJ, Jankowiak J, Hardt NA, Keijer J, Schutyser MAI, Nikifordias CV, Boom RM. Concept of further sustainable productions of foods. J Food Eng 2007;80(4):1188e93. https://doi. org/10.1016/j.jfoodeng.2015.07.010. [22] Taner T, Sivrioglu M. Energy-exergy analysis and optimisation of a model sugar factory in Turkey. Energy 2015;93:641e54. https://doi.org/10.1016/j. energy.2015.09.007. [23] Garg A, Sharma MP, Sharma V. Exergy and energy analyses of a sugarcane juice production and clarification unit. Int J Exergy 2016;19(1):78e90. https:// doi.org/10.1504/IJEX.2016.074268. [24] Taner T, Sivrioglu M. A techno-economic & cost analysis of turbine power plant: a case study for sugar plant. Renew Sustain Energy Rev 2017;78: 722e30. https://doi.org/10.1016/j.rser.2017.04.104. [25] Erbay Z, Koca N. Exergoeconomic performance assessment of a pilot-scale spray dryer using specific exergy costing method. Biosyst Eng 2014;122: 127e38. https://doi.org/10.1016/j.biosystemseng.2014.04.006. [26] Tsatsaronis G. Recent developments in exergy analysis and exergo-economics. Int J of Exergy 2008;5(5/6):489e99. https://doi.org/10.1504/IJEX.2008. 020822. [27] Lazzaretto A, Tsatsaronis G. SPECO: a systematic and general methodology for calculating the efficiencies and costs of thermal system. Energy 2006;31: 1257e89. https://doi.org/10.1016/j.energy.2005.03.011. [28] Mojarab Soufiyan M, Dadak A, Hosseini SS, Nasiri F, Dowlati M, Tahmasebi M. Comprehensive exergy analysis of a commercial tomato paste plant with a double-effect evaporator. Energy 2016;111:910e22. https://doi.org/10.1016/j. energy.2016.06.030. [29] Jekayenfa SO. Ergonomic evaluation and energy requirements of bread operations in south western Nigeria. Nutr Food Sci 2008;38(3):239e48. https:// doi.org/10.1108/00346650810871920. [30] Balkan F, Colak N, Hepbasli A. Performance evaluation of a triple-effect evaporator with forward feed using exergy analysis. Int J Energy Res

2005;29(5):455e70. https://doi.org/10.1002/er.1074. [31] Genc M, Genc S, Goksunger Y. Exergy analysis of wine production: red wine production process as a case study. Appl Therm Eng 2017;17:511e21. https:// doi.org/10.1016/j.applthermaleng.2017.02.009. [32] De Monte M, Padoano E, Pozzetto D. Waste heat recovery in a coffee roasting plant. Appl Therm Eng 2003;23:1033e44. https://doi.org/10.1016/S13594311(03)00033-4. [33] Aghbashlo M, Kainmehr MH, Arabhosseini A. Energy and exergy analyses of thin-layer drying of potato slices in a semi-industrial continuous band dryer. Dry Technol 2008;26(12):1501e8. https://doi.org/10.1080/ 07373930802412231. [34] Amjad W, Hensel O, Munir A, Esper A, Sturm B. Thermodynamic analysis of drying process in a diagonal-batch dryer developed for batch uniformity using potato slices. J Food Eng 2016;169:238e49. https://doi.org/10.1016/j. jfoodeng.2015.09.004. [35] Degerli B, Nazir S, Sorguven E, Hitzmann B, Ozilgen M. Assessment of the energy and exergy efficiencies of farm to fork grain cultivation and bread making process in Turkey and Germany. Energy 2015;93:421e34. https://doi. org/10.1016/j.jclepro.2015.10.031. [36] Mahmood A, Parshetti GK, Balasubramanian R. Exergy, energy and technoeconomic analyses of hydrothermal oxidation of food waste to produce hydro-char and bio oil. Energy 2016;102:187e98. https://doi.org/10.1016/j. energy.2016.02.042. [37] Luo X, Hu Jiahao, Zhao J, Zhang Bingjian, Chen Y, Mo Songping. Improved exergoeconomic analysis of retrofitted natural gas based cogeneration system. Energy 2014;72:459e75. https://doi.org/10.1016/j.energy.2014.05.068. [38] Gurturk M, Oztop HF, Hepbasli A. Comparison of exergoeconomic analysis of two different pearlitic expansion furnaces. Energy 2015;80:589e98. https:// doi.org/10.1016/j.energy.2014.12.015. [39] Ozdil NFT, Tantekin A. Exergy and exergoeconomic assessment of an electricity production system in a running waste water treatment plant. Renew Energy 2016;97:390e8. https://doi.org/10.1016/j.renene.2016.05.039. [40] Oni AO, Fadare DA, Adeboye LA. Thermo-economic and environmental analyses of a dry process cement manufacturing in Nigeria. Energy 2017;135: 128e37. https://doi.org/10.1016/j.energy.2017.06.114. [41] Bagdanavicius A, Jenkins N. Exergy and exergoeconomic analysis of a compressed air energy storage combined with a district energy system. Energy Convers Manag 2014;77:432e40. https://doi.org/10.1016/j.enconman.2013. 09.063. [42] The dairy handbook. first ed. Sweden: Tetra Pak Processing System; 2003. [43] Wright JA. The effect of minor components on milk fat crystallization behaviour, microstructure and mechanical properties [Ph.D Thesis]. Canada: The University of Guelph; 2001. [44] Jafaryani Jokandan M, Aghbashlo M, Mohtasebi SS. Comprehensive exergy analysis of an industrial-scale yogurt production plant. Energy 2015;93: 1832e51. https://doi.org/10.1016/j.energy.2015.10.003. [45] Atmaca A, Yumrutas R. Thermodynamic and exergoeconomic analysis of a cement plant: Part I e Methodology. Energy Convers Manag 2014;79:790e8. https://doi.org/10.1016/j.enconman.2013.11.053. [46] Atmaca A, Yumrutas R. Thermodynamic and exergoeconomic analysis of a cement plant: Part I e Methodology. Energy Convers Manag 2014;79: 799e808. https://doi.org/10.1016/j.enconman.2013.11.054. [47] Mojarrab Soufiyan M, Aghbashlo M, Mobli H. Exergetic performance assessment of a long-life milk processing plant: a comprehensive survey. J Clean Prod 2016;140(2):590e607. https://doi.org/10.1016/j.jclepro.2015.11.066. [48] Holman JP. Analysis of experimental data. In: Holman JP, editor. Experimental methods for engineers. Singapore: McGraw-Hill; 2001. p. 48e143. [49] Physical chemistry of foods. second ed. New York (USA): Marcel Dekker, Inc; 2003. [50] Boston G, Palfreyman K, Illingworth D, Cant E, Keen R. Milk fat product e a digital manual - version 2001. New Zealand Dairy Research Institute; 2001.