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Renewable Energy 34 (2009) 2373–2379

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Renewable Energy

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A comparison of the performances of adsorption and resorption refrigerationsystems powered by the low grade heat

L.W. Wang*, H.S. Bao, R.Z. WangInstitute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200240, China

a r t i c l e i n f o

Article history:Received 14 July 2008Accepted 3 February 2009Available online 5 March 2009

Keywords:AdsorptionResorptionRefrigerationHeat transferMass transfer

* Corresponding author. Tel.: þ86 21 34206056; faxE-mail address: lwwang@sjtu.edu.cn (L.W. Wang).

0960-1481/$ – see front matter � 2009 Elsevier Ltd.doi:10.1016/j.renene.2009.02.011

a b s t r a c t

In order to study the refrigeration performances of the resorption refrigeration technology, the resorp-tion working pair of BaCl2–MnCl2–NH3, which has the similar working requirements for the heat sourceand cooling source, and also could satisfy the similar refrigeration requirements with the adsorptionworking pair of CaCl2–NH3, is studied by simulation and experiments. In the simulation the mass transferresistance is not considered for the systems, and the refrigeration performances related with heattransfer performances are studied, results show that the resorption refrigeration system has a higherrefrigeration power and COP (coefficient of the refrigeration performance) because the refrigerationeffect is generated by the reaction heat compared to the latent heat of evaporation. After the simulationthe experimental test unit is constructed, and the experimental data are analyzed. Results show that theresorption rate is influenced by the critical mass transfer performance very much, and the refrigerationperformance is lower than that of adsorption system. The resorption system also has the problem of thelarger refrigeration power loss for the reason of the sensible heat requirement of low temperatureadsorber. How to improve the mass transfer performance of resorption system and decrease the influ-ence on the refrigeration power by the sensible heat requirement of low temperature adsorber will bethe key research directions for the application of resorption refrigeration systems.

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1. Introduction

The sorption refrigeration technology, which includes the solidsorption and liquid sorption processes, is a type of environmentalbenign and energy saving technology for the reason of the recoveryof low grade heat and the utilization of the refrigerants with zeroODP and GWP. The liquid sorption, i.e. absorption refrigeration,mainly includes the working pairs of LiBr–water and ammonia–water. The solid sorption mainly includes two types of workingprocess, one is adsorption refrigeration process, and another isresorption refrigeration process. The adsorption refrigerationworking pairs are mainly silica gel–water, activated carbon–methanol, zeolite–water, activated carbon–ammonia, chlorides–ammonia, etc. The resorption working pairs are mainlychlorides–ammonia.

There are mainly two refrigerating conditions, i.e. air condi-tioning and freezing condition. For the air conditioning condition,the LiBr–water absorption systems and the silica gel–wateradsorption refrigeration systems had already been commercialized[1,2]. For the freezing conditions that are lower than 0 �C, the

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available absorption working pair is ammonia–water. The availableadsorption working pairs are mainly activated carbon–methanol,activated carbon–ammonia, and chlorides–ammonia, and theavailable resorption working pairs are chlorides–ammonia.Compared with the ammonia–water absorption refrigerationworking pair, the advantages of the solid sorption working pairs areas follows:

(1) The solid sorption refrigeration technology is more suitable forthe situation with serious vibration because it utilizes the solidadsorbent, especially for the recovery of the waste heat forfishing boats and locomotives.

(2) The solid sorption refrigeration systems have more simplestructures because they do not need the rectification equip-ments nor a liquid pump [3].

On the development of adsorption freezing and ice makingsystems, there are mainly two aspects, one is for the utilization ofsolar energy, and another is for the utilization of waste heat offishing boats.

On the utilization of solar energy, Pons and Guilleminot [4]developed an activated carbon–methanol adsorption prototype,which produced almost 6 kg of ice per m2 of solar panel when theinsolation was about 20 MJ day�1, with a solar COP of 0.12. This rate

Fig. 1. The principle of adsorption and resorption refrigeration systems; (a) adsorp-tion; (b) resorption.

L.W. Wang et al. / Renewable Energy 34 (2009) 2373–23792374

of ice production remains one of the highest obtained by a lowtemperature heat source powered ice maker. Critoph [5] mentioneda solar vaccine refrigerator studied in his laboratory in the early1990s [6]. Such machine could maintain the cold box at 0.1 �Cduring the daytime. Erhard et al. [7] studied the adsorption icemaking test unit which adopts the SrCl2–NH3 as working pair and itis powered by the solar energy. This system has operated for about2000 cycles, and the COP is between 0.05 and 0.08, SCP is about10 W/kg. Lemmini and Errougani [8] developed an activatedcarbon–methanol adsorption refrigerator, and its lowest refrigera-tion temperature is lower than�11 �C for very high irradiation, andthe solar COP ranges between 5 and 8% while the irradiationbetween 12,000 and 28,000 kJ/m2.

On the recovery of waste heat for fishing boats, Zhu et al.firstly studied on an adsorption chilled water system which useszeolite–water as working pair [9], and then Huang and Mei hadstudied the feasibility of an adsorption ice maker which usesCaCl2–NH3 as adsorption working pairs [10]. Shanghai Jiao TongUniversity had developed the activated carbon–methanol andcompound adsorbent-ammonia adsorption ice makers [3,11,12]and freezing chillers [13], the optimal SCP is over than 700 W/kg,and corresponding COP is about 0.4 while the evaporatingtemperature is lower than �15 �C.

For the resorption process of chlorides, which is a type of solidsorption refrigeration technology, is firstly proposed for thethermal upgrading and heat pumping situation [14,15]. Vasieliev etal. firstly proposed to utilize the resorption system as a chemicalcooler for space applications [16], and then Li et al. [17] proposeda new type of cycle coupling the adsorption and resorptionrefrigeration processes together to improve the coefficientof refrigeration performance COP. Compared with the adsorptionrefrigeration processes, the advantages of resorption refrigerationtechnology are as follows:

(1) The resorption is more suitable for the serious vibrationcondition because there are not liquid refrigerant in the wholesystem.

(2) The resorption systems are more safe than the adsorptionsystems because it has lower pressure for the desorptionprocesses.

In this paper the principle, characteristics, theoretical perfor-mances of adsorption and resorption processes concerning chlo-rides–ammonia are compared, and the experimental results arealso analyzed.

2. Choice of adsorption and resorption working pairs

2.1. The working processes of adsorption and resorptionrefrigeration systems

The reaction formula for the reaction between metal chloridesand ammonia is as follows:

MaClb$ðNH3Þnþðm� nÞNH3

þ ðm� nÞDH4MaClbðNH3Þm at the temperature of Tr

(1)

where DH is the enthalpy of transformation for reaction (J mol�1),and Tr is the equivalent reaction temperature. M represents themetallic element. a and b are numbers of metallic and chlorineatoms, and m and n are equilibrium reaction coefficients.

The principle of basic adsorption and resorption refrigerationsystems are shown in Fig. 1.

As shown in Fig. 1(a), the adsorption refrigeration system mainlyincludes adsorber, condenser, ammonia tank, and evaporator. Theadsorption cycle includes two processes, and they are:

(1) The heating and desorbing process. In this process, the OV1 andOV3 in Fig. 1 (a) are open. The adsorber is heated by the mediaof heat source at Th, and takes up the heat of Qd of the heatsource at Th. The ammoniate chlorides decompose under theheating effect of heat source, and the ammonia condenses incondenser, and then the liquid flows to the ammonia tankthrough OV3 and accumulates there.

(2) The cooling and adsorbing process. In this process, the OV2 andTV are open. The adsorber is cooled by the cooling media at thetemperature of Ta, and it adsorbs the refrigerant inside evap-orator. The latent heat of vaporization in evaporator providesthe refrigerating effect.

The resorption refrigeration process is shown in Fig. 1 (b). Theresorption system mainly includes two components: an LTA (lowtemperature adsorber) and an HTA (high temperature adsorber).The salt that reacts at lower temperatures, such as BaCl2 and PaCl2always serves as the adsorbent inside the LTA, whereas the saltsthat react at higher temperatures, such as MnCl2 and NiCl2, alwaysserves as the adsorbent inside the HTA. The working processes ofresorption are as follows:

(1) The heating process. In this process, the LTA releases the heat tothe environment at the temperature of Ta, and the HTA isheated by the heat source at Th. The ammoniate chloridesinside the HTA decompose, and the ammonia gas is adsorbedby the salt inside LTA.

(2) The refrigerating process. In this process, the HTA releases theheat to the environment at the temperature of Ta, and ammo-niate chloride inside LTA decomposed under the adsorptionfunction of HTA. The reaction heat of decomposition of ammo-niate chloride inside LTA provides the refrigerating power.

2.2. Choice of working pairs for adsorption and resorption processes

The equilibrium reaction curves of chlorides (Fig. 2) areanalyzed in order to choose the appropriate working pairs.

Fig. 2. The p–T diagram for chlorides and ammonia.

L.W. Wang et al. / Renewable Energy 34 (2009) 2373–2379 2375

In the summer condition, the temperature of environment isalways about 30–32 �C. Considering the heat transfer temperaturedifference for the heat transfer media, the Ta for the adsorber isalways about 37–40 �C. The refrigerating temperature for thesystem is chosen as �25 �C.

(1) The choice of the adsorption working pair for the adsorptionrefrigeration process.

For the adsorption process, if the refrigerating temperature is�25 �C, then the evaporating point for the equilibrium line of ammoniain Fig. 2 is Eva. For this process the OV2 in Fig. 1a is open, then thepressure inside adsorber is always controlled by the restrained pres-sure, and it is equal to the pressure inside the evaporator, then underthe cooling temperature of about 40 �C, the available working pairs areCaCl2–NH3 and SrCl2–NH3. Because the CaCl2–NH3 has a better kineticsfor the adsorption process, the CaCl2 is chosen as the working pair forthe adsorption refrigeration.

For the desorption process, the condenser is cooled by thecooling media also at about 40 �C (point Con), corresponding theavailable highest desorbing temperature of heat source is about108 �C (Point C for CaCl2$(2–4)NH3).

(2) Choice of the working pair for resorption refrigeration process

In order to make a reasonable comparison, the condition for theresorption process, i.e. the parameters for heat source, environ-mental temperature and refrigeration temperature are all similarwith that of adsorption process.

For the refrigerating process, the available chlorides of lowtemperature salts are PbCl2 and BaCl2. While the refrigeratingtemperature is �25 �C, the refrigeration point of BaCl2 is LTd. In thisprocess the valve DV in Fig.1(b) is open, that means the pressure insideLTA is equal to the pressure inside HTA, then for the cooling tempera-ture of 40 �C, the available high temperature salt is MnCl2 (adsorbingpoint is HTa). For PbCl2 the reaction point for the �25 �C refrigeratingtemperature is E, and corresponding reaction point of MnCl2 is point F,that means the reaction of MnCl2 will occurs while the coolingtemperature is lower than about 65 �C, then 40 �C cooling temperatureis also available for the working pair of PbCl2–MnCl2–NH3.

For the heating process of resorption refrigeration system, whilethe adsorbing temperature of LTA is 40 �C, the reaction point for

PbCl2 and BaCl2 are G and LTa, respectively, and correspondingreaction point of MnCl2 are HTd and H, respectively. While the heatsource temperature is similar with that of adsorption cycles, i.e.about 110 �C, the available working pair is only MnCl2–BaCl2–NH3,in which the MnCl2 serves as the high temperature adsorbent, andthe BaCl2 serves as the low temperature adsorbent.

3. System design and performance simulation of adsorptionand resorption working pairs

3.1. System design

The system design is shown in Fig. 3. The working processes areas follows:

(1) For the heating period, the CaCl2 adsorber for adsorptionsystem, or the MnCl2 adsorber for resorption system, is heatedby the electric heating jacket, and the condenser for theadsorption system, or the BaCl2 adsorber for the resorptionsystem, is cooled by the cooling fan. For adsorption system therefrigerant desorbed by CaCl2 adsorber is condensed inside thecondenser, and for resorption system the refrigerant desorbedby the MnCl2 adsorber is adsorbed by the BaCl2 adsorber.

(2) For the refrigeration process, the CaCl2 for adsorption system,or the MnCl2 adsorber for resorption system, is cooled by thecooling fan, and the refrigeration effect of evaporator (orthe BaCl2 adsorber) is equaled by the chilling media inside thechilling jacket, which is put outside the evaporator (or theBaCl2 adsorber) for the refrigeration process. For the adsorp-tion system, the refrigerant inside evaporator is adsorbed byCaCl2 adsorber, and the evaporation of the refrigerant providesthe refrigeration effect. For the resorption system, thedesorbing effect of the BaCl2 adsorber provides the refrigera-tion effect.

3.2. Simulation models and results

The theoretical performance is analyzed under the condition ofthe CaCl2 mass in adsorption system and the BaCl2 mass inresorption refrigeration system are all 1 kg. In the simulation theadsorption and desorption processes are simulated mainly

Fig. 3. Design of the test unit for adsorption/resorption refrigeration systems. (a) Test unit; (b) resorption refrigeration system; (c) adsorption refrigeration system.

L.W. Wang et al. / Renewable Energy 34 (2009) 2373–23792376

according to the heat transfer performances, and the mass transferresistance of the system is neglected in order to simplify themodel.

(1) The model for the refrigerating process of adsorption system

According to energy conservation, the equation for the refrig-erating power of adsorption process is

Wref ¼�

ram �ma �dnmol

dt�mam=mca

�� ðmev � cam þmme

� cmÞ �dTev

dt(2)

where Wref is the refrigerating power (kW), t is time (s), ram is thelatent heat of vaporization of ammonia (kJ/(kg �C)), ma is theadsorbent mass (kg), Dnmol is the cycle quantity of ammonia (mol/mol), mam and mca are the molecular weight of ammonia andadsorbent (CaCl2), mev is the mass of ammonia inside the evapo-rator (kg), cam is the specific heat capacity of ammonia (kJ/(kg �C)),mme is the metal mass of evaporator (kg), cm is the specific heatcapacity of the metal for evaporator (kJ/(kg �C)), and DTev is thetemperature variation of the ammonia inside the evaporator (�C).

For the adsorber the energy conservation model is

WC ¼ a� Fa �dTa

dt

¼�

DHa �ma �dnmol

dt�mam=mca

�� ðmma

� cm þma � ca þma � nmol �mam=mca � camÞ �dTa

dt

��

ma �dnmol

dt�mam=mca

�� ðTa � TevÞ ð3Þ

where WC is the cooling power for the adsorption and coolingprocess, a is the heat transfer coefficient between cooling fan andadsorber (15.6 W/(m2 �C)), Fca is the heat transfer area of adsorber(m2), Ta is the temperature of adsorber (�C), DHa is the reaction heatat adsorption period (kJ/kg), mma is the mass of metal for adsorber(kg), ca is the specific heat capacity of adsorbent (CaCl2) (kJ/(kg �C)),Tev is refrigerating temperature (in evaporator) (�C).

(2) The model for the refrigerating process of resorption system

The equation for the refrigerating power of resorption system,which is generated by BaCl2 adsorber, is

WrefL ¼�

DHd �ma �dnmol

dt�mam=mca

�þ ðma � ca þmma

� cm þma � nmol �mam � camÞ �dTa

dt(4)

where WrefL is the refrigerating power (kW), DHd is the reactionheat for the desorption of adsorbent (kJ kg�1 K�1) working pair, mca

is the molecular weight of adsorbent (BaCl2). ca is the specific heatcapacity of BaCl2 (kJ/(kg �C), DTLT is the temperature variation of theBaCl2 adsorber (�C).

The equation for the MnCl2 adsorber, which is cooled by thecooling fan, is same with equation (3).

(3) The model for the heating process of adsorption and resorptionsystems

The equation for the heating process of CaCl2 adsorber is

Wh ¼ ��

DHd �ma �dnmol

dt�mam=mca

�þ ðma � ca þmma

� cm þma � nmol �mam=mca � camÞdTa

dt(5)

where Wh is the heating power provided by the electric heater.For the heating process of MnCl2 of resorption system, the

equation is same with eq. (5).The coefficient of the refrigeration performance (COP) is:

COP ¼ Wref

WhFor adsorption COP ¼ WrefL

WhFor resorption

(6)

The performances of adsorption and resorption refrigerationprocesses are simulated under the condition of the environmentaltemperature is 30 �C, heat source temperature is 130 �C,

L.W. Wang et al. / Renewable Energy 34 (2009) 2373–2379 2377

evaporating temperature is �10 �C, respectively. The equilibriumreaction performances of chlorides in Fig. 2 are also considered inthe simulation, and the results are shown in Fig. 4.

Fig. 4 shows that the optimal cooling power of adsorptionsystem and resorption system are 0.24 kW and 0.27 kW, and theCOP of adsorption refrigeration system and resorption system are0.4 and 0.46 respectively. Compared with that of adsorptionrefrigeration system, the refrigeration power and COP of resorptionsystem are improved 12.5% and 15% respectively.

For the resorption system, the cycle mass adsorption quan-tities for adsorption and resorption refrigeration systems aredifferent although the values of cycle molar adsorption quantityfor adsorption and resorption systems are all 4 mol/mol.Because the molecular weight of CaCl2 (110.98) is much less thatthat of BaCl2 (208.25), the mass cycle adsorption quantity ofadsorption system is much more than that of resorptionrefrigeration system under the condition of the mass of adsor-bent in CaCl2 adsorber and in BaCl2 adsorber are all 1 kg. Themass cycle adsorption quantity of ammonia inside CaCl2

adsorber is about 0.61 kg while the mass cycle adsorptionquantity of ammonia inside BaCl2 adsorber is only about0.33 kg/kg. The adsorption system mainly generates the coolingpower by the evaporation of the ammonia refrigerant, and itslatent heat of vaporization is about 1312 kJ/kg, whereas theresorption refrigeration system mainly generates the coolingpower by the reaction heat for the desorption of BaCl2, and itsvalue is about 2216 kJ/kg. Under the influences of these twoconditions, i.e. mass cycle adsorption quantity and the heat for

0.00

0.05

0.10

0.15

0.20

0.25

0 20 40 60 80t/ min

Wre

f/k W

0

0.1

0.2

0.3

0.4

0.5

CO

PCOP

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0 20 40 60 80t/ min

Wre

f/k W

0

0.1

0.2

0.3

0.4

0.5

CO

P

COP

Refrigerting power

Refrigerting power

b

a

Fig. 4. The refrigeration performances of adsorption and resorption refrigerationsystems. (a) Adsorption refrigeration system; (b) resorption refrigeration system.

the refrigeration process, the refrigeration power of resorptionsystem is 12.5% more than that of adsorption system.

For the heating process and cooling process, the reaction heat ofadsorbents occupies a large part of heating power, and the reactionheat for CaCl2 adsorbent and MnCl2 adsorbent is about 2449 and2789 kJ/kg respectively. Because the values of adsorbents aresimilar, then under the condition of the cycle adsorption quantityof resorption system is much less than that of adsorption system,the optimal cycle time of resorption system, which is about 27 minis much shorter than that of adsorption system (in Fig. 4) becauseof the less heat needed for the less cycle adsorption quantity ofrefrigerants. The corresponding optimal COP for resorption systemis about 15% more than that of adsorption system.

4. The experimental results of adsorption and resorptionsystems

4.1. The experiments of resorption systems

A test unit is set up in order to testify the adsorption andresorption refrigeration performances, and the photo of the testunit is shown in Fig. 5. In the system the mass of adsorbent in lowtemperature adsorber is 71 g, and the mass of adsorbent in hightemperature adsorber is 85 g.

The cooling power is calculated by the equation:

Qref ¼ mwacwaDtwa (7)

where mwa is the water mass inside the chilling water jacket (kg),cwa is the specific heat capacity of water (kJ/kg �C), Dtwa is thetemperature difference of the water inside the chilling water jacket(�C).

For the calculation of the cycle adsorption quantity for resorp-tion cycle, the equations are

mal$DxNH3$DHlr ¼

�malcpal þmalDxNH3

cam

�$Dtl

þmmlcm$Dtm þ Qref

0DxNH3¼

malcpal$Dtl þmmlcm$Dtm þ Qref

mal$DHlr þmal$Dtl(8)

where mal is the mass of adsorbent inside the low temperatureadsorber (kg), DxNH3

is the cycle adsorption quantity (kg/kg), DHlr isthe reaction heat of the BaCl2–NH3 (kJ/kg), cpal is the specific heatcapacity of adsorbent in low temperature adsorber (kJ/(kg �C), cam

is the specific heat capacity of ammonia, Dtl is the temperaturechange of adsorbent, mml is the mass of metal for adsorber, cm is thespecific heat capacity of metal, and Dtm is the temperature changeof the metal material for adsorber.

For the calculation of the heating power, the equation for theheating power Qhs is

Qhs ¼�

mahcph þmal$DxNH3

�$Dth þmmhcmDtmh

þmal$DxNH3$DHhr (9)

where mah is the mass of adsorbent inside the high temperatureadsorber, cph is the specific heat capacity of the adsorbent, Dth is thetemperature change of adsorbent inside high temperatureadsorber, mmh is the mass of metal for high temperature adsorber,Dtmh is the temperature change of the metal, DHhr is the reactionheat of the MnCl2–NH3.

The coefficient of the refrigeration (COP) and the specific coolingpower (SCP) are:

COP ¼ Qref

Qhs; SCP ¼ Qref

thc$mal(10)

Fig. 5. The photo for the test unit.

L.W. Wang et al. / Renewable Energy 34 (2009) 2373–23792378

4.2. The experiments of adsorption systems

For the adsorption refrigeration system of CaCl2–NH3, under thecondition that the evaporator generates the cooling power to thechilling water jacket, the cooling power of evaporator is tested, andthe system performances are evaluated under the condition thatthe adsorbent in the adsorber is same with that in the lowtemperature adsorber of resorption systems.

The refrigeration cooling power calculation is same as eq. (7).For the calculation of the cycle adsorption quantity, the equation is

ma$DxNH3$DHam ¼

�me�maDxNH3

�cam$Dtþmemcm$DtmþQref

0DxNH3¼ mecam$Dtþmemcm$DtmþQref

ma$DHrþma$cam$Dt(11)

where ma is the mass of adsorbent in the adsorber, DHam is thelatent heat of evaporation of ammonia. me is the ammonia mass inthe evaporator, Dt is the temperature change of the ammonia in theevaporator, mem is the metal mass of the evaporator.

The heating cooling power is similar with eq. (9).

4.3. The experimental results analysis

The refrigeration temperatures of adsorption and resorption aretested, and they are shown in Fig. 6.

-10

-5

0

5

10

1520

25

30

35

0 5 10 15 20 25 30t / min

T ref / oC

Adsorption system

Resorption system

Fig. 6. The refrigerating temperature of adsorption and resorption systems.

The refrigeration quantity of resorption system is about 19.79 kJwhile the cycle time is 20 min, and the corresponding COP and SCPare 0.157 and 232 W/kg respectively. The refrigeration quantity ofadsorption system is about 22.56 kJ, and the corresponding COPand SCP are 0.28 and 265 W/kg.

The experimental results are much different from the simula-tion results in Fig. 4. This is mainly caused by the low reactionpressure inside the resorption system. The reaction pressure ofresorption is much lower than that of adsorption while the refrig-eration temperature is the same. For example, while the evapo-rating temperature is�5 �C, the pressure for the adsorption systemis 0.355 MPa, and the pressure for resorption system is only about0.03 Mpa. Under such a condition, the mass transfer performance ofresorption system is influenced, and the reaction rate is very slow.The resorption system is also easier has the leakage problembecause its pressure fluctuates from the positive value to thenegative value in the whole cycle.

In the real application, the resorption system also has a problemof the cooling power loss, which is caused by the sensible heat ofadsorbent and the metal of adsorber. For the adsorption system, iftwo adsorbers are adopted in the system, then the evaporator couldprovide the cooling power continuously at a stable refrigerationtemperature. But for the resorption system, because the refrigera-tion effect is provided by the low temperature adsorber, which isalways under the condition of the similar temperature with theenvironment before it switches to the refrigeration mode, thatmeans the adsorber must be cooled from the environmentaltemperature to the refrigeration temperature before it provides therefrigeration power. Under such a condition the reasonable designof a low temperature adsorber is very essential for the decrease ofthe refrigeration power loss for resorption refrigeration system.

5. Conclusions

The resorption technology, which is generally utilized for theheat pump technology, is proposed to be utilized for the refriger-ation process recently. Compared with the adsorption refrigerationsystem, the resorption system is more reliable and safer becausethere is no liquid in the system, and its pressure is also much lowerthan that of adsorption system that utilizes ammonia as refrigerant.

In order to study the resorption refrigeration performances, theresorption refrigeration technology is compared with the

L.W. Wang et al. / Renewable Energy 34 (2009) 2373–2379 2379

adsorption refrigeration technology, and the theoretical analysisshows that under the condition the environmental temperature is30–32 �C, refrigeration temperature is �25 �C, and the heatingsource temperature is less than about 110 �C, the optimal adsorp-tion working pair is CaCl2–NH3, and the optimal resorption workingpair is MnCl2–BaCl2–NH3.

A tested unit is designed for the test of resorption refrigerationperformances, and the adsorption and resorption refrigerationperformances are simulated while the heat transfer performancesare considered. The results show that the resorption refrigerationsystem has a higher COP and refrigeration power because itgenerates the cooling power by the reaction heat while theadsorption refrigeration system generates the cooling power by thelatent heat of ammonia, which is about 50% percent of the reactionheat of chlorides–ammonia.

The test unit is constructed, and then the resorption refrig-eration performances are tested and calculated, and resultsshow that the resorption refrigeration system has severalproblems, the first one is the critical mass transfer performancecaused by the lower reaction pressure, which is only about 1/10of the value of the reaction pressure for the adsorption refrig-eration system. The worse mass transfer performance not onlyleads to a very slow reaction rate, but also increases the possi-bility of leakage. The second problem is that the low tempera-ture adsorber, which generates the refrigerating power, isalways at the environmental temperature before it switches tothe refrigeration mode, and then the sensible heat of adsorberutilizes lots of refrigeration power.

For the real application of resorption refrigeration technology,the improvement of mass transfer performance and the reasonabledesign will be very essential for the improvement of the refriger-ation performances.

Acknowledgement

This work was supported by Key project of Natural ScienceFoundation of China under the contract No. 50736004 and projectof Natural Science Foundation of China under the contract No.50806043.

References

[1] Wang DC, Xia ZZ, Wu JY, Wang RZ. Study of a novel silica gel–water adsorptionchiller. Part I. Design and performance prediction. International Journal ofRefrigeration 2005;28:1073–83.

[2] Saha BB, Koyama S, Lee JB, Kumahara K, Alam KCA, Hamamoto Y, et al.Performance evaluation of a low-temperature waste heat driven multi-bedadsorption chiller. International Journal of Multiphase Flow 2003;29:1249–63.

[3] Wang LW, Wu JY, Wang RZ, Xu YX, Wang SG, Li XR. Study on the performanceof activated carbon–methanol adsorption systems concerning heat and masstransfer. Applied Thermal Engineering 2003;23:1605–17.

[4] Pons M, Guilleminot JJ. Design of an experimental solarpowered, solid-adsorption ice maker. Journal of Solar Energy Engineering d Transactions ofthe ASME 1986;108(4):332–7.

[5] Critoph RE. Carbon–ammonia systems – previous experience, current projectsand challenges for the future. In: Proceedings of the international sorption andheat pump conference (ISHPC 2002), Shanghai, China; 2002.

[6] Critoph RE. Laboratory testing of an ammonia carbon solar refrigerator. In:Proceedings of the solar world congress (ISES), Hungary; 1993.

[7] Erhard A, Spindler K, Hahne E. Test and simulation of a solar powered solidsorption cooling machine. International Journal of Refrigeration1998;21(2):133–41.

[8] Lemmini Fatiha, Errougani Abdelmoussehel. Experimentation of a solaradsorption refrigerator in Morocco. Renewable Energy 2007;32:2629–41.

[9] Zhu RQ, Han BQ, Lin MZ. Experimental investigation on an adsorption systemfor producing chilled water. International Journal of Refrigeration1992;15(1):31–4.

[10] Huang NF, Mei N. The research of CaCl2–NH3 adsorption ice maker for fishingboat. Journal of Ocean University of Qingdao 1995;6:81–7 [in Chinese].

[11] Wang LW, Wang RZ, Wu JY, Xu YX, Wang SG. Design, simulation and perfor-mance of a waste heat driven adsorption ice maker for fishing boat. Energy2006;31:244–59.

[12] Wang LW, Wang RZ, Lu ZS, Xu YX, Wu JY. Split heat pipe type compoundadsorption ice making unit for fishing boats. International Journal of Refrig-eration 2006;29:456–68.

[13] Wang K, Wu JY, Xia ZZ, Li SL, Wang RZ. Design and performance prediction ofa novel double heat pipes type adsorption chiller for fishing boats. RenewableEnergy 2008;33(4):780–90.

[14] Neveu P, Castaing J. Solid–gas chemical heat pumps: field of application andperformances of the internal heat of reaction recovery process. Heat RecoverySystems & CHP 1993;13(3):233–51.

[15] Choi HK, Neveu P, Spinner B. System modelling and parameter effects ondesign and performance of ammonia based stelf thermochemical transformer.In: Proceedings of the international absorption heat pump conference,Quebec, Montreal; 1996. p. 505–12.

[16] Vasieliev LL, Nikanpour D, Antuh A, Snelson K, Vasiliev Jr L, Lebru A. Multisalt-carbon chemical cooler for space applications. In: Proceedings of the Interna-tional absorption heat pump conference. Munich, Germany; 1999. p. 579–83.

[17] Li TX, Wang RZ, Oliveira RG, Wang LW. Performance analysis of an innovativemultimode, multisalt and multieffect chemisorption refrigeration system.AIChE Journal 2007;53(12):3222–30.