Small Organic Rankine Cycle Coupled to Parabolic Trough Solar Concentrator

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IV International Seminar on ORC Power Systems, ORC2017 IV International on ORC Systems, 13-15Seminar September 2017,Power Milano, Italy ORC2017 13-15 September 2017, Milano, Italy

Small Organic Rankine Cycle Coupled to Parabolic Trough Solar The 15th International Symposium on District Heating and Trough Cooling Solar Small Organic Rankine Cycle Coupled to Parabolic Concentrator Concentrator Assessing the feasibility of using the heat demand-outdoor

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U. Caldiño-Herreraaa, Laura Castroaa, O.A. Jaramillobb, J.C. Garciaaa*, Gustavo Urquizaaa, temperature function for aFrancisco heat *,demand forecast U. Caldiño-Herrera , Laura Castro , long-term O.A. Jaramillo Gustavo Urquiza , a , J.C. Garcia Floresdistrict a Francisco Flores b a Universidad 1001, c México UniversidadI.Autónoma dela,b,c Estado Chamilpa, Cuernavaca, Morelos, 62209, Andrić *, deA.Morelos, PinaAv. , P. Ferrãoa, J.Col. Fournier ., B. Lacarrière , O. Le Correc b Universidad delRenovables, Estado de Morelos, Av. Universidad 1001, Col. Cuernavaca, 62209,Morelos, México 62580, México InstitutoAutónoma de Energías Universidad Nacional Autónoma de Chamilpa, México, Priv. XochicalcoMorelos, s/n, Temixco, b a Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco s/n, Temixco, , México IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, Morelos, 1049-00162580 Lisbon, Portugal c

b Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France

Abstract Abstract In this paper, the design and performance of small Organic Rankine Cycle (ORC) coupled to parabolic trough solar collector (PTC) In this paper,The the system design and performance small Rankine (ORC) coupledThis to parabolic trough solar collector (PTC) Abstract are showed. is analyzed usingofthe firstOrganic and second laws Cycle of thermodynamics. small ORC is designed to provide 10 are showed. The 18 system analyzed the first andtosecond laws of thermodynamics. Thisofsmall ORC isare: designed to provide 10 kWe for almost hoursisevery day using and also energy heat water. The main components this system a) parabolic trough kWe for almost hours every day and alsoaddressed energy and toinheat water. The as main this system are: and a) for parabolic trough District heating18networks commonly literature onecomponents of theR245fa mostofeffective solutions decreasing the solar concentrators (PTC), b)are thermal storage system c)the ORC system, which uses as working fluid a radial turbine solar concentrators (PTC), b)from thermal system c) ORC system, which R245faregion aswhich working and radialradiation turbine gas ORC emissions the storage building sector.and systems high investments arefluid returned the heat asgreenhouse expander. The system is designed to operate inThese Temixco, cityrequire located at uses the central of México. Theathrough solar as expander. The ORC system istodesigned tothe operate Temixco, city located at the central region ofinMéxico. Thewas solar radiation sales. Due to the changed conditions andin building renovation heat demand the future could decrease, database of Temixco was usedclimate compute estimated performance of thepolicies, proposed ORC system. Simulation carried out database of Temixco was used compute theand estimated performance of the The proposed system. Simulation wasfor carried out prolonging the return period. using Matlab andinvestment CoolProp. ThetoORC power efficiency were computed. mass ORC flow and thermal load stored the PTC using Matlab and CoolProp. The power efficiency were the computed. The mass flow and thermal load stored thedemand PTC Theare main scope of this paper is ORC to assess the and feasibility of using heat demand – outdoor temperature function forfor heat loop shown. loop are shown. forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings vary Published in both construction © 2017 Thethat Authors. by Elsevierperiod Ltd. and typology. Three weather scenarios (low, medium, high) and three district © 2017 The Authors. Published by Elsevier Ltd. renovation scenarios were developed (shallow, deep).International To estimate the error, obtained heat demand values were © 2017 The Authors. Published by Elsevier Ltd. intermediate, Peer-review under responsibility of the scientific Peer-review under responsibility of the scientific committee committee of of the the IV IV International Seminar Seminar on on ORC ORC Power Power Systems. Systems. compared with from a dynamic heat demand model,ofpreviously developed Seminar and validated by the authors. Peer-review underresults responsibility of the scientific committee the IV International on ORC Power Systems. The results showed that powered, when only weather change is considered, the margin of error could be acceptable for some applications Keywords: Small ORC, solar thermal oil storage Keywords: ORC, solar powered, oil storage (the errorSmall in annual demand wasthermal lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. © 2017 The Authors. Published by Elsevier Ltd. * Corresponding author. Tel.: +52 777of3the 29 79 84; fax: +52 777 3 29 of 79 The 84. 15th International Symposium on District Heating and Peer-review under responsibility Scientific Committee * Corresponding author. Tel.: +52 777 3 29 79 84; fax: +52 777 3 29 79 84. E-mail address: [email protected] Cooling. E-mail address: [email protected]

1876-6102 ©Heat 2017demand; The Authors. Published bychange Elsevier Ltd. Keywords: Forecast; Climate 1876-6102 2017responsibility The Authors. of Published by Elsevier Ltd. of the IV International Seminar on ORC Power Systems. Peer-review©under the scientific committee Peer-review under responsibility of the scientific committee of the IV International Seminar on ORC Power Systems.

1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling.

1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the IV International Seminar on ORC Power Systems. 10.1016/j.egypro.2017.09.097

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1. Introduction As is well known, the Rankine Cycle has been used to get mechanical power through a thermodynamic cycle where a fluid, usually water, is evaporated, expanded and condensed. This cycle requires a source of energy with a high content of enthalpy because steam have to reach pressures of 8.6 MPa and temperatures of 500○C, in order to have high efficiencies. However, there are many sources with low content of enthalpy, like: waste heat of any industrial process, geothermal sources or thermal solar energy. In order to use the aforementioned energy sources, the Rankine cycle requires an organic working fluid and in this case it is called Organic Rankine Cycle (ORC). The advantages of the ORC are: simple structure, easy maintenance, high reliability, wide variety of working fluids (hundreds of organic substances) and diversity of possible energy sources [1]. As stated before, solar thermal energy is one of the heat sources that could be used by ORC system and some of the researches or technological developments are listed readily. Delgado-Torres and Garcia-Rodriguez [2], carried out a theoretical analysis of ORC coupled to solar thermal collectors for desalination applications. Twelve organic substances and four types of solar collectors were analyzed. Butane, isobutene, R245fa and R245ca were selected as working fluids for and ORC with a heat transfer fluid configuration. S. Quolin et al. [3], carried out a thermodynamic analysis of an ORC powered by trough solar concentrator, with an output power of 3 kW. PTC used monoethylene glycol as a heat transfer fluid. The analysis showed that the global efficiency of Solkhatherm was 7.9% and R245fa was 6.9%. Villarini et al. [4], reviewed some ORC applications (like desalination treatment, inverse osmosis and electricity generation) powered by solar thermal energy with the capability of work during 14 hours every day. Borunda et al. [5], presented a new configuration (called direct feed-storage configuration) of a commercial PTC (NEPsolar) coupled to an ORMAT ORC and to a thermal storage tank. This configuration was analyzed in case of a cogeneration for a textile industry. The ORMAT power block required 11075 kWt to produce 8.3 MWt and 1.3MWe. Therminol 55 was the oil used for the PTC and n-butane for ORC System. Taccani et al. [6] 2016; designed and tested a small ORC powered by a PTC. This ORC used R245fa as a working fluid and delivered an electricity power out of 670 W. Giuffrida [7], using a realist thermodynamic model, evaluated the effect of the working fluid on the performance of scroll expander for small ORC (0.75 -2 kW), he found that HCFO-1233zd(E) could be used for a solar based ORC system. Despite the diversity of small solar powered ORC proposed up to now, if they are carefully built and operated, it is highly attractive since it is possible to obtain more than 10% of efficiency [4]. Nomenclature h s is ρ T P V 𝑚𝑚̇ 𝑄𝑄̇ 𝑄𝑄𝑠𝑠𝑠𝑠𝑠𝑠 𝑃𝑃𝑅𝑅 η HE V W A, B, C, D, M, N a, b, c, d Etdi

Enthalpy Entropy Isentropic Density Temperature Pressure Volume Mass flow rate Heat flux Stored thermal energy Pressure rate Efficiency Heat exchanger Control Valve Power

kJ/kg kJ/kg K kg/m3 K Pa m3 kg/s J/s J Dimensionless Dimensionless

Therminol streams R245fa stream Total direct irradiance per day

kg/s kg/s W/m2

W

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In this paper, the thermodynamic analysis of a small ORC (10kWe) powered by parabolic trough solar concentrators is showed. Thermodynamic properties were estimated using Matlab and CoolProp. The system has a thermal tank to store up to 11 hours of thermal load, so the ORC system could operate 18 hours in a continuous way. Power and efficiency were estimated using first and second thermodynamic laws. Also, the mass flow through the PTC and to the storage tank are showed. This ORC system is designed to provide electricity for a cluster of houses. In addition, energy released by the condenser will be used to heat water for domestic use or to heat a water pool. 2. Model and data The proposed ORC system consists of two closed loops. The first loop (in blue on Figure 1) uses Therminol 55 as working fluid (Table 1) and it accomplishes two objectives: the first one is to capture the solar radiation energy through a solar concentrator (Table 2) and transfer it to the organic working fluid for the ORC on a heat exchanger, the second objective is to store part of the thermal energy transferred to Therminol in isolated tanks so this stored thermal energy could be used during the time where solar radiation is not available or enough to operate de ORC. This loop consists of the solar concentrators, storage tanks for the heated Therminol, a heat exchanger that interacts with the ORC loop, a pump to move the Therminol through the loop and an auxiliary heat exchanger. The auxiliary heat exchanger HE Aux could provide complementary heat to HE1 when the thermal load is low. The control valves V1 and V2 regulate the Therminol mass flow in order to maintain a constant heat flow rate of 160 kW to the heat exchanger HE1. The mass flow rate through the solar collector array varies to satisfy the energy demand of ORC loop and to store thermal energy. According to the global features of PTC used here (Table 2), the output temperature could reach a temperature between 200-220 OC, so for this reason a 200 OC output temperature from the solar collector array was selected. This output temperature is kept constant using control valves to regulate the Therminol mass flow.

Fig 1 ORC system powered by Parabolic Trough Solar Concentrators

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Table 1 Therminol 55 properties

Tank 1 storage volume

20.65 m3

Temperature of Therminol in tank 1

200 OC

Therminol flow to heat exchanger HE1 (constant)

0.434 kg/s

Therminol flow to reservoir tanks (variable)

peak 0.98 kg/s

Liquid density

868 kg/m3

Cp

2170 J/kg K

Table 2 Global features PTC (PolyTrough 1200) [5]

Aperture Area

28.8 m2

Aperture width

1.2 m

Thermal peak power for every module (with 1000 W/m2)

15.8 kW

Length

24 m

PTC efficiency

0.55

Outlet temperature

200-220 OC

Modules

34

Total aperture area (for all 34 modules)

979 m2

Additional features can be consulted in [5]

The second loop (in purple on Figure 1) is the ORC and consists of the following devices: 1) a pump for increasing the pressure of R245fa, as a working fluid (taking it from saturated liquid to sub-cooled condition), 2) an evaporator (HE1) where Therminol 55 transfers its heat energy to R245fa and it changes from sub-cooled liquid to overheated vapor, 3) a radial turbine where the vaporized working fluid is expanded and the mechanical energy is extracted, 4) a condenser where the vapor from turbine outlet is taken to saturated liquid conditions. The low pumping work is one of the reasons to use R245fa as working fluid for an ORC, according to Borsukiewicz [8] R245fa requires about 3.15% of the work produced by the ORC expander. In addition, R245fa has low evaporating and critical properties, which is recommend when the ORC is coupled to solar concentrators. The main properties of R245fa are: molecular weight 134 kg/mol, boiling point 14.8 °C (@ 1 Atm), Freezing Point -71 °C (@ 1 Atm), critical temperature 154.04 °C and critical pressure 36.4 bar

Fig 2 Month average values of solar direct irradiance at Temixco, México [9].

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The thermodynamic behavior of the system depends on some fixed variables that must be set according to the design conditions like power output and available radiation energy. For this work, the electrical power generated through the system has a target of 10 kWe and about 520 kW as thermal peak during the daytime operation from the parabolic through solar concentrators. The solar irradiance variation is presented in Fig. 2 as the month average values for the first six months of 2016. The total direct irradiance (Etdi) per day is about 5426 W/m2, this quantity was computed by integration of the daily direct irradiance during the aforementioned months. The total thermal energy (from 8:00 a.m. to 4:20 p.m.) per day is computed by Eq. 1 and this thermal energy is transferred by the PTCs to Therminol 55 stream, which is split in two streams: one stream is stored in tank 1 and the other one is sent to ORC loop. 𝑄𝑄̇𝑃𝑃𝑃𝑃𝑃𝑃 = 𝐸𝐸𝑡𝑡𝑡𝑡𝑡𝑡 𝜂𝜂𝑃𝑃𝑃𝑃𝑃𝑃 𝐴𝐴𝑃𝑃𝑃𝑃𝑃𝑃

(1)

The Therminol mass flow at D stream carries the necessary thermal energy to operate the ORC. During the morning (before 9:00 am) or evening (after 4:00 pm), the N stream maintains thermal energy to operate the ORC. The Therminol mass flow at D stream is calculated according to the desired thermal load 𝑄𝑄̇𝑂𝑂𝑂𝑂𝑂𝑂 (160 kW) at the ORC loop (Eq. 2). 𝑄𝑄̇𝑂𝑂𝑂𝑂𝑂𝑂

𝑚𝑚̇𝐷𝐷 =

𝐶𝐶𝐶𝐶𝑡𝑡 (𝑇𝑇𝑡𝑡𝑖𝑖𝑖𝑖 −𝑇𝑇𝑡𝑡𝑜𝑜𝑜𝑜𝑜𝑜 )

𝑉𝑉1 = 𝜌𝜌

𝑡𝑡 𝐶𝐶𝐶𝐶𝑡𝑡 (𝛥𝛥𝛥𝛥)

(2)

where sub-index indicates: t for Therminol 55, D the mass flow through HE 1, in and out the inlet and outlet Therminol flows at HE 1. The total volume of tank 1 is computed from: 𝑄𝑄𝑠𝑠𝑠𝑠𝑠𝑠

(3)

where 𝑄𝑄𝑠𝑠𝑠𝑠𝑠𝑠 is the thermal energy stored in the tank 1 and it is computed as follow: 𝑄𝑄𝑠𝑠𝑠𝑠𝑠𝑠 = 𝑄𝑄̇𝑃𝑃𝑃𝑃𝑃𝑃 ∗ 𝑡𝑡𝑠𝑠𝑠𝑠𝑠𝑠 − 𝑄𝑄̇𝑂𝑂𝑂𝑂𝑂𝑂 ∗ 𝑡𝑡𝑂𝑂𝑂𝑂𝑂𝑂

(4)

tsun is the operation time of the PTC (8.3 hours per day) and t ORC is the time when ORC works with thermal energy fed directly from PTCs. The thermodynamic behavior of the ORC depends on several parameters like the available heat energy on the evaporator, the mass flow rate, the operating pressures and the working fluid. On this work, as mentioned previously, the available energy on the evaporator depends on the first loop of the system and for this analysis, it is of 160 kW. The rest of the global features for the ORC are shown on Table 3. Table 3 Global features of a 10 kW ORC Description

Quantity

Dimension

Mechanical power (Ws)

11.6

kW

Heat exchanger 1

145.15

kW

Heat exchanger 2 (condenser)

133.61

kW

Electric production

10.4

kW

Mass flow (R245fa)

0.65

kg/s

Pressure expansion ratio (expander)

4

Dimensionless

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The methodology for ORC thermodynamic analysis is described below and the thermal properties are calculated through CoolProp linked to Matlab. CoolProp allow to know the state thermodynamic properties by knowing any two properties of that state. The device efficiencies and capacities involve at the ORC loop are shown on Table 4. Device

Table 4 Device capacities and efficiencies Capacity or efficiency

Therminol pump e efficiency

0.7

Therminol pump capacity

1.5 Hp

Exchanger 1 efficiency

0.91

ORC Pump (Wpump)

¾ Hp

ORC Pump efficiency (ηpump)

0.48

ORC expander efficiency

0.7

Starting from pump inlet state, it is set to be saturated liquid at 303 K, this temperature corresponds to a saturating pressure of Pa=178 kPa, from these two known properties, the full thermodynamic state is calculated. The pump outlet conditions are defined by Eq. 5, as function of ORC pump and the pump efficiency. The pressure at this state is Pb: 𝑃𝑃𝑏𝑏 =

𝜂𝜂𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 𝑊𝑊𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 𝑄𝑄

+𝑃𝑃𝑎𝑎

(5)

Considering an isentropic process the enthalpy at this state is calculated from Pb and sa.. Using the definition of isentropic efficiency 𝜂𝜂𝑠𝑠 , the actual value of enthalpy at pump outlet is ℎ𝑏𝑏 = ℎ𝑎𝑎 +

(ℎ𝑏𝑏 𝑖𝑖𝑖𝑖 −ℎ𝑎𝑎 ) 𝜂𝜂𝑖𝑖𝑖𝑖

(6)

With hb and Pb, the pump outlet state (or evaporator inlet state) is fully determined. For the evaporating process, the available heat from Therminol loop is transferred to the ORC working fluid. This heat flux transfer is described by the following equation 𝑄𝑄̇𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒 = 𝑚𝑚̇𝑂𝑂𝑂𝑂𝑂𝑂 (ℎ𝑐𝑐 − ℎ𝑏𝑏 )

(7)

ℎ𝑑𝑑 = ℎ𝑐𝑐 − 𝜂𝜂𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡 (ℎ𝑐𝑐 − ℎ𝑑𝑑𝑑𝑑 )

(8)

𝜂𝜂_𝑡𝑡 = (ℎ_𝑐𝑐 − ℎ_𝑑𝑑)/(ℎ_𝑐𝑐 − ℎ_𝑏𝑏 )

(9)

The evaporating process is considered to be isobaric, so once the value of ℎc is calculated the full evaporator outlet/turbine inlet state can be evaluated. The turbine outlet state is defined by the pressure ratio and turbine isentropic efficiency. The actual turbine outlet enthalpy is computed with the turbine efficiency ηturb, Knowing these two properties for turbine outlet state the remaining unknown properties can be calculated. At this point the ORC is fully defined and the thermodynamic behavior is evaluated. The parameters calculated for this work are: thermal efficiency, second law efficiency and mechanical power output.

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𝜂𝜂_𝐼𝐼𝐼𝐼 = 𝜂𝜂_𝑡𝑡/(1 − 𝑇𝑇_𝑎𝑎/𝑇𝑇_𝑐𝑐 )

(10)

𝑊𝑊̇𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡 = 𝑚𝑚̇𝑂𝑂𝑂𝑂𝑂𝑂 (ℎ𝑐𝑐 − ℎ𝑑𝑑 )

(11)

3. Case study results Following the methodology described previously and considering the features of Table 3 for a 10 kWe power output. The ORC thermodynamic states for these parameters are shown in Table 5 and in Fig. 3. Table 5 R245fa flow streams properties in the ORC Loop ORC R245fa flow stream properties

P (bar)

T (K)

h (kJ/kg)

s (kJ/kg-K)

Density (kg/m3)

(a)

1.78

303

239.41

1.13

1325

(b)

7.48

303

239.56

1.13

1327

(c)

7.48

351.63

462.87

1.78

41.17

(d)

1.87

321.67

444.96

1.81

9.88

Fig 3 Thermodynamic T-s diagram for the ORC using R245fa.

It is important to note that the ORC is operated at constant conditions despite the daily solar radiation variation. This is due to the Therminol loop varies the mass flow through solar collector array (Fig. 4), maintaining a fixed thermal load at ORC evaporator inlet. Therminol loop has the capacity to store thermal load to operate the ORC when the solar radiation is low. The mechanical power generated under this operating conditions is 11.6 kW and considering an electric generator efficiency of 0.9, the electric power is 10.4 kW. While the thermal input of 160 kW is kept constant, the ORC will deliver 11.6 kW every day for at least 18 hours. The weather of Temixco helps to reach such condition, because the

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minimum annual temperature is about 20.5 °C, during December. However the annual performance of two systems (Therminol loop and ORC loop) will be reported in a further work.

Fig 4 Stored Therminol volume and Therminol mass flow through PTC or to the thermal tank.

Thermal efficiency is 8.02 % this means that 91.98% of the energy available in the evaporator is wasted on the condenser. This allows to use the remaining heat for other applications like domestic water heating. In this case, considering an efficiency of 0.9, the condenser could deliver up to 124 kW for heating domestic water. This energy could heat a stream water of 1.9 kg/s, increasing water temperature from 23 °C (average annual temperature at Temixco) to 41 °C. The second law efficiency is 57.99%. 4. Conclusion According to the thermodynamic analysis, the proposed ORC powered by solar PTC will provide 10.4 kWe in a continuous way during 18 hours, to be used for small cluster of houses. The system is designed to operate in Temixco, a city in the central part of Mexico. ORC uses R245fa as a working flow, while the solar PTC loop uses Therminol as a working flow. The cluster of houses could use the energy released by the condenser (124 kW) to heat water for domestic use. The efficiency was 8.02 % and the second law efficiency was 57.99%. References [1] Bao J, Zhao L. A review of working fluid and expander selections for organic Rankine cycle. Renewable and Sustainable Energy Reviews, 2013, 24, 325-342. [2] Delgado-Torres AM, García-Rodríguez L. Analysis and optimization of the low-temperature solar organic Rankine cycle (ORC). Energy Conversion and Management, 2010, 51(12), 2846-2856. [3] Quoilin S, Orosz M, Hemond H, Lemort V. Performance and design optimization of a low-cost solar organic Rankine cycle for remote power generation, Solar Energy, 2011, 85(5), 955-966. [4] Villarini M, Bocci E, Moneti M, Di Carlo A, Micangeli A. State of art of small scale solar powered ORC systems: A review of the different typologies and technology perspectives, 2014, Energy Procedia, 45, 257-267. [5] Borunda M, Jaramillo OA, Dorantes R, Reyes A. Organic Rankine Cycle coupling with a Parabolic Trough Solar Power Plant for cogeneration and industrial processes. Renewable Energy, 2016, 86, 651-663. [6] Taccani R, Obi JB, De Lucia M, Micheli D, Toniato G. Development and Experimental Characterization of a Small Scale Solar Powered Organic Rankine Cycle (ORC). Energy Procedia, 2016,101, 504-511. [7] Giuffrida, A. Modelling the performance of a scroll expander for small organic Rankine cycles when changing the working fluid. Applied Thermal Engineering, 2014, 70(1), 1040-1049. [8] Borsukiewicz-Gozdur A. Pumping work in the organic Rankine cycle. Applied Thermal Engineering 2013,51(1–2):781–6. [9] Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Esolmet, http://esolmet.ier.unam.mx/index.html, Consulted January 3rd 2017. [9] https://eif-wiki.feit.uts.edu.au/_media/technical:renewables:111010_polytrough1200b_techspec_v10.pdf