Experimental study of ice slurry production system using direct contact heat transfer of RC318 and water in a horizontal pipe

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Energy Procedia 158 Energy Procedia 00(2019) (2017)4495–4501 000–000 www.elsevier.com/locate/procedia

10th International Conference on Applied Energy (ICAE2018), 22-25 August 2018, Hong Kong, 10th International Conference on Applied Energy China(ICAE2018), 22-25 August 2018, Hong Kong, China

Experimental study of ice slurry production system using direct The 15th International on District Heating and Cooling Experimental study of iceSymposium slurry production system using direct contact heat transfer of RC318 and water in a horizontal pipe contact heat transfer of RC318 and water in a horizontal pipe Assessing the feasibility of demand-outdoor a, using the heat a, Yaokang Zhanga,b , Lin Su *, Kaijun Dong †, Tengqing Liuaa a,b a, a, Yaokang Zhang for , Lin Su *, Kaijun district Dong †, Tengqing Liu temperature function a long-term heat demand forecast Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China a a

b University of Chinese Academy of Sciences, 100049, China 510640, China Guangzhou Institute of Energy Conversion, Chinese AcademyBeijing of Sciences, Guangzhou

a b c Academy Sciences, Beijing 100049, China I. Andrića,b,c*, A. University Pinaa, ofP.Chinese Ferrão , J. ofFournier ., B. Lacarrière , O. Le Correc b

a

IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal

b Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France Abstract c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France Abstract With the direct contact ice production technique, ice blockage around the injector, large refrigerant charge and difficulty in With the direct contact ice production technique, iceorder blockage around these the injector, large charge andjetdifficulty in separating the refrigerant from water always occur. In to overcome problems, the refrigerant combined of a spiral (SPJT) and separating refrigerant from watertoalways occur. In orderice to production, overcome these problems, the combined a spiral jetThe (SPJT) a horizontalthe PVC pipe is developed achieve continuous and RC318 is selected as the of refrigerant. effectand of a Abstract horizontal PVCofpipe developed to continuous ice production, RC318 israte, selected as the refrigerant. TheCOP effectand of rotational speed theiscompressor onachieve water temperature decrement, iceand production ice packing factor (IPF), rotational speed the compressor on water temperature decrement, ice study. production rate, ice packing factor COPspeed and coefficient of iceofproducing performance (CIPP) is investigated in this The results show that as the (IPF), rotational District heating are commonly (CIPP) addressed in the literature as one of The the most effective solutions decreasing the coefficient ice networks producing performance is investigated in this study. results show that the for rotational increases, a of faster drop of water temperature and a higher ice production rate are obtained, which result inas higher IPF under speed fixed greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat -3 kg/kJ increases, a faster drop water temperature andspeed a higher rate obtained, which result in higher IPF under fixed at duration. However, an of increase in rotational leadsicetoproduction a decrease inare COP. The maximum CIPP is 6.64×10 sales. Due to the changed climate conditions and leads building heat maximum demand inCIPP the future could kg/kJ decrease, at duration. However, an increase in rotational speed to arenovation decrease inpolicies, COP. The is 6.64×10 rotational speed of 2700rpm. Moreover, at high rotational speed of 2820rpm, the cooling capacity becomes worse at-3 the later prolonging the investment return period. at high rotational rotational of 2700rpm. of 2700rpm 2820rpm,isthe cooling as capacity becomes worse at the later stage of icespeed production process.Moreover, Conclusively, the rotational speed of considered the optimal working condition. The of main of thisprocess. paper isConclusively, to assess the feasibility of using heat demand – outdoor as temperature heat demand stage ice scope production the rotational speedthe of 2700rpm is considered the optimalfunction workingfor condition. forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 Copyright © 2018 Elsevier Ltd. All rights reserved. ©buildings 2019 The Authors. Published by Elsevier Ltd. and typology. Three weather scenarios vary in both construction period (low, medium, high) and three district Copyright ©that 2018 Elsevier Ltd. Allresponsibility rights reserved. Selection and peer-review under of the scientific committee of the 10th International Conference on Applied This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand on values were th International Conference Applied Selection and peer-review under responsibility of the scientific committee of the 10 Energy (ICAE2018). Peer-review under responsibility of the scientific committee ofpreviously ICAE2018developed – The 10th International Conference on Applied Energy. compared with results from a dynamic heat demand model, and validated by the authors. Energy (ICAE2018). The results when only weather considered, marginrotational of error speed could be acceptable for some applications Keywords: ice showed blockage;that SPJT; horizontal PVC pipe;change RC318;iscontinuous ice the production; (the erroriceinblockage; annual demand was lower forcontinuous all weather scenarios considered). However, after introducing renovation Keywords: SPJT; horizontal PVCthan pipe; 20% RC318; ice production; rotational speed scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the 1.The Introduction decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and 1. Introduction renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the Air-conditioning loadvalues demand duringcould the warmest of summer days,parameters reaching for up to in commercial coupled scenarios). The suggested be used hours to modify the function the70% scenarios considered,and and Air-conditioning load demand during the warmest hours of summer days, reaching up to 70% in commercial and office buildings [1], intensifies the peak load. To alleviate this problem, ice thermal energy storage is considered as improve the accuracy of heat demand estimations.

office buildings [1], intensifies theelectric peak load. alleviate thistoproblem, thermal energy storage is considered as an effective approach for shifting loadsTo from on-peak off-peak ice hours. an© effective for shifting electricLtd. loads from on-peak to off-peak hours. 2017 The approach Authors. Published by Elsevier Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. * Corresponding author. Tel.: +86 20 38455713. E-mail address: [email protected]

87021959. E-mail address: [email protected] [email protected] * Corresponding author. Tel.: +86 20 38455713. Keywords: Heat demand; Forecast; Climate change * Corresponding author. Tel.: +86 20 87021959. E-mail address: [email protected] 1876-6102 Copyright © 2018 Elsevier Ltd. All rights reserved. Selection peer-review under responsibility the scientific 1876-6102and Copyright © 2018 Elsevier Ltd. All of rights reserved. committee of the 10 th International Conference on Applied Energy (ICAE2018). Selection and peer-review under responsibility of the scientific committee of the 10 th International Conference on Applied Energy (ICAE2018). 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 © 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of ICAE2018 – The 10th International Conference on Applied Energy. 10.1016/j.egypro.2019.01.762

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Ice-on-coil system is a commercial ice thermal energy storage. It uses a submerged coil through which a refrigerant is circulated and ice accumulates on the outside of the coil. However, due to the low thermal conductivity of ice, the efficiency of heat transfer is seriously reduced with the increasing of ice layer thickness. With a view to improving the thermal performance of ice storage systems, a direct contact ice slurry production system is being developed. Whereas, some problems still exist when this system is put into practice, such as ice blockage around the injector, large refrigerant charge, and difficulty in separating the refrigerant from water [2]. Aiming at the ice blockage around the injector, Thongwik et al. [3] proposed that an interesting method to avoid this problem is to produce slurry ice. Meanwhile, they reported that when the composition is water/oil/Tween60 at 100/6/1 by volume, slurry ice is formed. However, pure ice can’t be obtained by this method. Stowasser et al. [4] applied resistant heating to the refrigerant feeding device, but the use of resistant heating represented a persistent energy consumption. Accordingly, it is desirable that ice could be formed continuously without any additive and additional energy consumption. In this study, a SPJT and a horizontal PVC pipe are employed to overcome this problem completely. The refrigerant diffuses into a continuous flow of water under the guidance of SPJT, which ensures ice crystals being formed are also dispersed and not easily accumulated into larger ice blocks. At the same time, the flowing water can take away the ice crystals around SPJT in time. Besides, the inner wall surface of PVC pipe is rather smooth, which can avoid the adhesion of ice crystals effectively. Under the combined action of the SPJT, the flowing water and the PVC pipe, continuous ice production can be achieved. In previous studies, different types of refrigerants, R22 [5], R123 [6], CO2 [3], FC-84 [7] and R600 [8], were used in direct contact evaporator for ice slurry production. However, R22 and R123 are harmful to the ozone layer by reason of their nonzero ODP, and will be faded out eventually. CO2 and FC-84 don’t involve phase change during cooling and ice formation period, and can only use their sensible heat. Thus, the system using these two refrigerants has larger refrigerant charge and lower ice production rate. R600 has poor safety ratings because of its flammability. Consequently, the selection of the refrigerant is a pressing task to be dealt with. In this work, RC318, a type of perfluorocycloalkane, is selected as the dispersed phase. RC318 has a zero ODP and a safety ratings of A1. Moreover, since the normal boiling point of RC318 is slightly lower than 0℃, RC318 can evaporate after taking heat directly from water. As a result, the charge amount of RC318 will be reduced due to the use of latent heat and RC318 can also be easily separated from water due to its final gas state. Although some researches have been done on the direct contact ice production system, the problem of ice blockage around the injector hasn’t been solved thoroughly. What’s more, most of previous studies were concerned on the heat transfer in the direct contact evaporator and discussed the effects of different operating parameters on the volumetric heat transfer coefficient. However, there is a lack of research on the performance of the system. As investigated by Kiatsiriroat [9], the performance of the direct contact ice production system depends on two factors, the compressor speed and the mass flow rate of the refrigerant. Therefore, the objective of this present study is to achieve continuous ice production and to investigate the system performance under different compressor rotational speeds. In order to achieve these objectives, the combined of a SPJT and a horizontal PVC pipe is developed to prevent ice blockage around the injector. Meanwhile, RC318 is selected as the refrigerant, and water is chosen as the phase change material. The effects of different compressor rotational speeds on the water temperature decrement, ice production rate, IPF, COP, and CIPP are experimentally investigated. 2. Experimental details 2.1. Experimental apparatus and procedure Fig.1 shows the experimental set-up which consists of a direct contact heat exchanger (DCHE), a SPJT, an ice slurry storage tank, a compressor, a plate heat exchanger, an expansion valve and a water chiller. The DCHE is a horizontal PVC pipe with 3m length and 45mm inner diameter. A SPJT is inserted at the entrance of the horizontal PVC pipe. The physical diagram of the SPJT is shown in Fig.2 whose type is SPJT JJCO1/2 120 316L. The ice slurry storage tank is composed of two connected carbon steel tanks, which are both 80cm diameter and 130cm length. Two sight glasses are mounted on both sides of the upper tank for observing inside phenomenon. The refrigerant vapor is condensed in the plate heat exchanger by 7℃chilled water supplied by the water chiller, and then it flows through the expansion valve to reduce the pressure and temperature. The cold two phase refrigerant



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is injected into flowing water uniformly through the SPJT and extracts heat from water directly and then the mixture of the refrigerant and the water flows into the ice slurry storage tank. As a result, the water temperature decreases till ice crystals appear. The refrigerant, after receiving heat, becomes vapor and leaves the ice slurry storage tank to the compressor. The water is pumped to the entrance of the horizontal PVC pipe for the next circulation. P1 T1

P Pressure transducer

Mass flow meter

P0

Control valve

T PT100 transducer

Compressor DCHE

4 P4 T

T8 P2 T2

SPJT

Ice slurry storage tank Pump

T5

Water chiller

Plate heat exchanger

T6

T7

Pump

P3 T3

Expansion valve

Fig.1. Schematic diagram of the experimental set-up.

Fig.2. Physical diagram of the SPJT.

In this study, the initial water temperature is around 11℃. The volume of water is 584L. The inner circulation water flow rate is 3.8m3/h. The rotational speed is set to 2580rpm, 2700rpm and 2820rpm, respectively. The temperature is measured by calibrated PT100 having ±0.1℃ accuracy. The pressure is measured by pressure transducers having ±0.25% accuracy. The mass flow rate is measured by mass flow meter having ±0.5% accuracy. The power consumption is measured by power meter having ±0.5% accuracy. 2.2. Selection of the refrigerant The refrigerant used in direct contact ice slurry production systems must: (1)be insoluble and not react with water; (2)be easily separated from water; (3)have appropriate working pressure and phase transition temperature; (4)be eco-friendly and safe. Table 1 shows the comparison of the refrigerant properties from RC318 used in this study with those of the other researchers. It’s found that RC318 can meet the above requirements. The specific properties and characteristic of RC318 are shown in Table 2. Table 1.Comparison of the refrigerant properties of direct contact ice slurry production system 1. Refrigerant

Insoluble in water

Not react with water

Exclude Cl atom

Phase change heat transfer

safety

R22

● ● ● ● ● ● ● ●

● ● ○ ● ● ○ ● ●

○ ○ ● ● ● ● ● ●

● ● ○ ○ ○ ● ● ●

● ○ ● ● ○ ● ○ ●

R123 CO2 N2 FC-84 R134a R600 RC318

Table 2. Properties and characteristic of RC318 fluid [10].

1

Refrigerant

Molecular weight (kg/kmol)

Normal boiling point(℃)

Critical temp (℃)

Critical pressure (MPa)

Safety group

ODP

RC318

200.03

-6.0

115.2

2.778

A1

0

● represents that the refrigerants have this property. ○ represents that the refrigerants don’t have this property.

GWP 100yr 10250

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Fig.3 shows the saturated vapour pressure of RC318, R22, R134a and R123. From Fig.3, the saturated pressure of R22 and R134a are much higher than that of RC318. Thus, the higher pressure endurance capability of the system is required. Conversely, the saturated pressure of R123 is lower than atmospheric pressure during ice formation period. In consequence, the air is easily mixed into the system, and the airproofing is required to be strict. The saturated pressure of RC318 is slightly higher than atmospheric pressure near 0℃ and the increasing is gradual. Therefore, the ice slurry production system can be operated at lower pressure, and the efficiency and reliability will be greatly improved. Saturated vapor pressure(MPa)

1.2

RC318 R123 R134a R22

1.0 0.8 0.6 0.4 0.2 0.0

-10

0

10

20

30

Temp(℃)

Fig.3. The variation of saturated vapor pressure of each refrigerant with temperature [11].

3. Data reduction 3.1. Performance parameters With the assumption of no heat transfer between the system and environment, the cooling capacity is defined as:

Q  m r hr ,o  hr ,i  



(1)

Where, Q is the cooling capacity, kW. m r is the mass flow rate of the refrigerant, kg/s. hr,o is enthalpy of RC318 at the outlet of ice slurry storage tank, kJ/kg. hr,i is enthalpy of RC318 at the inlet of DCHE, kJ/kg. The ice production rate can be calculated by Eq (2): mice (2) vice  tice Where, vice is the ice production rate, kg/min. Δmice is the mass increment of ice during Δtice, kg. Δtice is time duration of ice production, min. The IPF is the percent by weight of small particles of ice formed to the initial water, and can be calculated as: m (3) IPF  ice mw Where, mice is the total mass of ice, kg. mw is initial mass of water, kg. The CIPP is used to express performance of ice slurry production system. It is defined as: v (4) CIPP  ice W Where, W is the power consumption, kW. 3.2. Theoretical model When the thermal insulation of system is well, according to the lumped model [3], the temperature of water in the storage tank during the sensible heat period can be mr hr ,o  hr ,i  

Twt  t  Twt 

mwCpw

t

(5)



Yaokang Zhang et al. / Energy Procedia 158 (2019) 4495–4501 Yaokang Zhang et al. / Energy Procedia 00 (2018) 000–000 t  t

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t

Where, Tw is the water temperature at moment t+Δt, K. Tw is the water temperature at moment t, K. Cpw is the specific heat capacity of water, 4.2kJ/(kg.K). Moreover, during ice formation period, the water temperature is constant at its freezing point and the mass of ice during a time interval can be predicted from mr hr ,o  hr ,i  

mice 

Where, rw is latent heat of freezing of water, 335kJ/kg.

rw

(6)

tice

4. Results and discussion 4.1. Direct contact heat transfer between RC318 and water during the sensible heat period Fig.4 exhibits the decrease of water temperature inside storage tank for three different rotational speeds during sensible heat period compared with that evaluated from the theoretical model. In Fig.4, it is found that as the rotational speed increases, the drop of water temperature becomes faster and the beginning of ice crystals formation comes earlier at the identical initial water temperature. The beginning time of ice formation at the rotational speed of 2820 rpm is about 6 min and 10 min earlier than that at 2700 rpm and 2580 rpm, respectively. Due to an increase in mass flow rate of RC318 with the increasing of compressor rotational speed, a higher cooling capacity is obtained, which accelerates the drop of water temperature. Moreover, the predicted water temperature are well agreed with the measured value of water temperature in the storage tank, as presented in Fig.4. The temperature predicted from the model decreases slightly faster than the measured value since an ideal adiabatic storage tank is approximated. 12

2.6 2580rpm-Exp. 2580rpm-Model 2700rpm-Exp. 2700rpm-Model 2820rpm-Exp. 2820rpm-Model

Tw (℃)

8 6 4 2 0

0

10

20

30

40

50

2580rpm 2700rpm 2820rpm

2.5 Ice production rate (kg/min)

10

60

t (min)

Fig.4. Comparison of water temperature decreasing from the experiments and the model.

2.4 2.3 2.2 2.1 2.0 1.9

50

100

150

200

250

t (min)

Fig.5. The variation of ice production rate during ice formation period at various compressor rotational speeds.

4.2. Direct contact heat transfer between RC318 and water during ice formation period During ice formation period, the water temperature remains constant and the enthalpy change is attributed to latent heat of freezing. Fig.5 depicts the variation of ice production rate of RC318 ice producing system with time for different rotational speeds. It is known that in Fig.5 with increasing the rotational speed from 2580rpm to 2820rpm, the ice production rate obviously increases. Moreover, it can be found that in Table.3 the average ice production rate at rotational speed of 2820rpm is 8.5% and 24.1% higher than that of 2700rpm and 2580rpm, respectively. Due to increasing of the rotational speed, the mass flow rate of RC318 increases, which results in higher cooling capacity. As described in Eq. (6), a higher ice production rate will be obtained. It also can be seen from Fig.5 the variation of ice production rate with time nearly remain constant at rotational speeds of 2580rpm and 2700rpm. However, at rotational speed of 2820rpm, the ice production rate stays at about 2.55kg/min firstly, then drops in gradual by 8.51% and eventually remains at about 2.35kg/min. The main reason

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why the ice production rate remain constant at lower rotational speed is that the evaporating and condensing conditions and the mass flow rate of R318 almost remain constant in the ice formation period. The drop of ice production rate occurs at the rotational speed of 2820rpm is attributed to the decline efficiency of the compressor. The compressor used in our study is a water-ring vacuum pump. When the rotational speed arises, the power consumption increases, which leads to more exhaust heat transfer to the water-ring in the compressor. The waterring evaporates, which will deteriorate the efficiency of the compressor. Less mass flow rate of RC318 recycling in the ice producing system decreases the cooling capacity. Until the water-ring maintains stable again, the ice production rate eventually remains at about 2.35kg/min. Table 3. The average ice production rate and IPF for various rotational speeds of compressor. Rotational speed

2580 (rpm)

2700 (rpm)

2820 (rpm)

The average ice production rate (kg/min)

1.955

2.236

2.426

IPF (2 hours)

40.18%

45.94%

49.85%

Furthermore, seen in Table.3, IPF, 2 hours after the ice formation beginning, increases with an increase in rotational speed due to higher ice production rate with higher rotational speed. Fig.6 shows the ice slurry production deposited in the storage tank. 4.3. The system performance analysis The variation of COP along time under different rotational speeds are displayed in Fig.7. Seen from Fig.7, it is easy to find that the COP all decrease sharply with time during the sensible heat period. This can be explained that the evaporating temperature of RC318 goes down gradually with the reduction of the water temperature. As a result, more and more RC318 keeps liquid and sinks to the bottom of the tank. The mass of cycling RC318 becomes less until the water temperature maintains at 0℃. Hence, the mass flow rate of RC318 decreases with time, which results in the reduction of cooling capacity with time. Meanwhile, the power consumption is nearly constant. Consequently, the COP decrease with time at different rotational speeds during the sensible heat period. This phenomenon also reveals that the refrigerant loss occurs in separation process, but less refrigerant charge will avoid this problem. It is also can be seen in Fig.7, during ice formation period, the COP both remain approximately constant at rotational speed of 2580rpm and 2700rpm. However, when the rotational speed is 2820rpm, the COP stabilizes around 2.14 during the first 40 minutes, and starts to decrease steadily thereafter until it finally maintains at about 1.98. In case of rotational speed of 2820rpm, it is ascribe to the reduced efficiency of the compressor. 3.0

2580rpm 2700rpm 2820rpm

2.8

COP

2.6 2.4 2.2 2.0 1.8

0

50

100

150

200

250

t (min)

Fig.6. The physical figure of ice slurry in the storage tank.

Fig.7. The variation of COP at various compressor rotational speeds.

In addition, from Fig.7, it is noted that the higher the rotational speed, the lower the COP. Specifically speaking, as shown in Table.4, the average COP at rotational speed of 2580rpm is 0.87% and 9.43% higher than that of 2700rpm and 2820rpm, respectively. This is the result of the increase of the power consumption is much faster than that of the cooling capacity with the increase of the rotational speed.

As for the CIPP of the RC318 ice producing system, as listed in Table.4, the system at 2700rpm rotational speed shows high CIPP by up to 0.15% and 8.32% in comparison with that at 2580rpm and 2820rpm, respectively.



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Even though system at 2700rpm rotational speed shows slightly 0.86% lower COP than that at 2580rpm, the CIPP of system at 2700rpm rotational speed is higher than that at 2580rpm. Furthermore, the average ice production rate at 2700rpm rotational speed is 14.37% faster than that at 2580rpm, indicating that more ice can be produced at the same duration at 2700rpm. In general, system at 2700rpm rotational speed shows the best performance. Table 4. The system performance parameters for various rational speeds of compressor. Rotational speed

2580(rpm)

2700(rpm)

2820(rpm)

The average cooling capacity (kW)

11.37

12.89

13.89

The average COP

2.32

2.30

2.12

The average CIPP(10-3kg/kJ)

6.63

6.64

6.13

5. Conclusions In this study, the combined of a SPJT and a horizontal PVC pipe is proposed to achieve continuous ice production. RC318 is selected as the disperse phase, and the flowing water is chosen as the continuous phase. The system performance under three different compressor rotational speeds is investigated. Based on the experimental investigations, the following conclusions could be drawn. 1) When the rotational speed increases, a faster drop of the water temperature is obtained. Moreover, the theoretical model can predict the water temperature quite well. 2) A higher rotational speed results in higher ice production rate and higher IPF under fixed duration. In addition, when the rotational speed is 2580rpm and 2700rpm, the ice production rate is almost constant during the whole ice formation process. While at 2820rpm, the ice production rate decreases by 8.51% at the later stage. 3) The COP decreases with increasing rotational speed. Besides, the COP decreases sharply with time during the sensible heat period, and during the ice formation period, the COP has the same tendency with the ice production rate under different rotational speeds. The maximum CIPP is 6.64×10-3kg/kJ at the rotational speed of 2700rpm. 4) The compressor rotational speed of 2700rpm is considered as the optimal working condition. Acknowledgements This work is supported by Natural Science Foundation of Guangdong Province, China (No.2015A030310333), the Science and Technology Planning Project of Guangdong Province, China (No.2017B090907027) and the Science and Technology Planning Project of Tianhe District, Guangdong Province, China (No.201705YH091). References [1] M.A. Karim. Experimental investigation of a stratified chilled-water thermal storage system. Applied Thermal Engineering, 2011, 31(11-12): 1853-1860. [2] X. Zhang, K. Zheng, L. Wang, et al. Analysis of ice slurry production by direct contact heat transfer of air and water solution. Journal of Zhejiang University SCIENCE A, 2013, 14(8): 583-588. [3] S. Thongwik, N. Vorayos, T. Kiatsiriroat, et al. Thermal analysis of slurry ice production system using direct contact heat transfer of carbon dioxide and water mixture. International communications in heat and mass transfer, 2008, 35(6): 756-761. [4] W.F. Stowasser, K.A. Miller. Water cooling method and apparatus employing liquid nitrogen: U.S. Patent 3,672,182. 1972-6-27. [5] T. Kiatsiriroat, S. Vithayasai, N. Vorayos, et al. Heat transfer prediction for a direct contact ice thermal energy storage. Energy conversion and management, 2003, 44(4): 497-508. [6] F. Isobe, Y.H. Mori. Formation of gas hydrate or ice by direct-contact evaporation of CFC alternatives. International journal of refrigeration, 1992, 15(3): 137-142. [7] M.N.A. Hawlader, et al. Analyses of ice slurry formation using direct contact heat transfer. Applied Energy, 2009, 86(7-8): 1170-1178. [8] T. Hu, H. Guan, K. Dong, et al. Performance analysis of a novel ice slurry generation system. HV&AC, 2017,47(4):87-91. (In Chinese). [9] T. Kiatsiriroat, P. Siriplubpla, A. Nuntaphan. Performance analysis of a refrigeration cycle using a direct contact evaporator. International Journal of Energy Research, 1998, 22(13): 1179-1190. [10] B.F. Tchanche, G. Papadakis, G. Lambrinos, et al. Fluid selection for a low-temperature solar organic Rankine cycle. Applied Thermal Engineering, 2009, 29(11-12): 2468-2476. [11] REFPROP. NIST Standard Reference Database 23, Version 9.0.