Performance Characteristics of Refrigerants

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1 2017 IJSRST Volume 3 Issue 4 Print ISSN: Online ISSN: X Themed Section: Science nd Technology Performnce Chrcteristics of Refrigernts Ajoko, Tolumoye John Deprtment of Mechnicl/Mrine Engineering, Fculty of Engineering. Niger Delt University, Wilberforce Islnd, Byels Stte, Nigeri ABSTRACT The incresing concern of climte chnge is the lrming issue to the designers, distributors nd end time users of refrigertion nd ir conditioning systems. The continuous use of convectionl refrigernts with chlorine molecules hs been the bottleneck nd drwbcks set to cover by reserch. Thus, the current study is designed to bridge some of these reserch gps. Therefore, detiled evlution of refrigernts with the id of trining simultor cpble of nlysing the thermo-physicl properties nd performnce of some selected blend of refrigernts is the focl point of the study. The study cretes decision policies on the selection of the best nd ecofriendly refrigernt(s) to be used in the refrigertion/ir conditioning systems. However, simulted results confirm HFC R 134 blend of refrigernts s the best due to its high proficient coefficient of performnce (COP) vlue of 3.23 nd 2.84 ginst 2.88 nd 2.38; 1.33 nd 2.53; 1.40 nd 1.85 for R 12, R 22 nd R 600 respectively for thermosttic expnsion vlve (TEV) nd Cpillry tube opertion modes. It lso ttests tht R 134 nd R 12 s estblished from the prcticl results re the most pproprite refrigernts for domestic nd industril heting respectively. Hence, results re justifible nd the process of this study could be used s tool for the selection process of refrigernts with zero ozone depleting potentils. Keywords: Air-Conditioning, Cpillry tube, Coefficient of Performnce, Refrigernts, Refrigertion cycle, Stbiliztion point, Thermosttic Expnsion Vlve, TPS Simultor. I. INTRODUCTION Refrigertion over the yers hs developed to be very importnt process needed round the globe due to its wide rnge of usefulness nd importnce. It hs impcted positively on industriliztion, griculturl sector, preservtion of medicl nd surgicl ids, oil refining nd synthetic rubber mnufcturing/metls tretment, conservtion of food products/beverges nd finlly for the comfortbility of mn. Though with this numerous benefits ttched to the refrigerting process; the chllenges from this system to the environment cnnot be over emphsized or forgotten in hste. Severl reports by scholrs hve shown tht the vrious working fluids used in the refrigertion system hve contributed mjorly on the depletion of the ozone lyer. These globl hrmful scenrios of refrigernts hve destroyed the strtospheric region leding to serious issues of globl wrming [1-4]. Due to this ctstrophe, conventionl refrigernts with chlorine molecules s found in the hlocrbons such s the chloro fluoro crbon (CFC), hydro chloro fluoro crbon (HCFC) nd unsturted orgnic compounds with chlorine rdicl ll of primry refrigernt clss should be voided nd llow to phse out from the system. However, in reviewed reserch work; mthemticl modelling process hs been developed to check zero tolernce of ozone depleting refrigernts in the refrigertion systems.[5, 6]. Menwhile, the vilbility of wide rnge of refrigernts is quite tsking to scertin the suitble refrigernt for prticulr refrigertion system nd process for certin working conditions, since different fluids (refrigernt) hve the desirble properties nd chrcteristics in different degree. Hence, the study for the performnce chrcteristics for refrigernts hs become necessry in order to evlute n ecofriendly refrigernt which is bound to protect the environment from dredful substnces. In this direction, mny positive contributions hve so fr been mde. As estblished in reviewed literture, refrigernt could be considered for selection to be used if it meets the three bsic criteri it must be sfe, be environmentlly friendly, nd must provide excellent IJSRST My 2017 Accepted: 23 My 2017 My-June-2017 [(2)4: ] 243

2 performnce benefit [7]. Consequently, different nlysis nd experiments hve been crried out over the yers to determine the best refrigernts to be used for prticulr refrigertion system considering either one or the entire criterion s stted bove. In line with this perspective, it is unveiled tht theoreticl investigtion for the performnce of R 410 in replcement of R 22 in n ir conditioner with the sme het exchngers nd compressors of the sme efficiency is tested fesible with the following resons. The COP of R 410 is proven to be better thn R 22 t ll pressures, with less hrmful influence on the environment though their thermophysicl properties seems to be similr, hence substitution requires miniml ltertions in the refrigertion system [8]. A similr study exmines the performnce nlysis of two sub-clsses of the Freon group; CFC-12 nd HFC At the end of the performnce investigtion, report ttests tht even though the CFC-12 clss is widely used in both residentil nd commercil pplictions, the interntionl lw set forth in the Montrel Protocol hs put CFC-12 on phse out schedule due to its Ozone Depletion Potentil. However, HFC-134 hs been estblished s drop-in-substitute for CFC-12 on the bses of their similrities in thermodynmic properties nd performnce [9]. Also theoreticl ssessment of different commercil refrigertion systems in terms of nnul energy consumption nd environmentl impct ws investigted by reserchers. In their study, it ws defined tht R 744 inorgnic refrigernt should be employed bck for subcriticl conditions in the refrigertion system from the thermo-physicl point of view. Thus, the refrigernt is of firly better thermodynmics properties thn HFCs s reported in their studies [10],[11]. Menwhile the evlution performnce of different refrigernts such s R 600, R 134, R 290, R 22, R 410, nd R 32 in study ws crried out in n optimized evportor to determine the impct on the system COP. Report from tht study revels high spred of COP up to 11.7% for theoreticl cycle nlysis without ccounting for the evportor effects [12]. Thus, to mintin emission free environment, it is necessry to nlyze the performnce chrcteristics of refrigernts tht psses through refrigertion cycle. Therefore this process is crried out with the id of simultion models known s Theorem Proving System (TPS) Simultor. II. SETUP OF PRACTICAL STIMULATOR As stted erlier tht the primry purpose of this study is to identity nd evlute the performnce chrcteristics of refrigernts s they pss through refrigertion process or cycle. Thus, in ccomplishing this objective, the selected refrigernts will be tested using TPS simultor. However, refrigernts for this purpose re selected rndomly from different clsses nd groups of refrigernts which bsolutely possess different chemicl formultion nd structure. Apprently, results obtined from the simultion my be used to represent ll the refrigernts in tht clss or group since they hve similr chrcteristics nd chemicl structures. Hence, refrigernts with the following chemicl nmes nd formuls re used to represent refrigernt under the hlocrbon compounds. Dichloro-difluoro methne (CCl 2 F 2 ) - R 12, monochloro-difluoro methne (CHClF 2 ) R 22 nd tetrfluoroethne (CH 2 FCF 3 ) R 134 representing CFC, HCFC, HFC groups respectively; while butne (C 4 H 10 ) - R 600 stnds for the hydrocrbon compounds (HC). Figure 1 show digrm of the TPS simultor used for the simultion process. Figure 1: Refrigertion nd Air Conditioning TPS Simultor. source: [13] 244

The simultor is incorported with some mechnicl components such s compressor, condenser, expnsion system nd n evportor; nd other devices. III.

region to high temperture region s it is stted in Clusius sttement on the second lw of thermodynmics tht it is impossible for selfcting mchine working in cyclic process unided by ny externl gency, to

In generl note, they hve triple function such s reducing refrigernt temperture in the cooling circuit s it moves to the evportor.

Figure 4 is presenttion of n expnsion unit in the trining simultor Figure 2: Compressor of refrigertion system The condenser or condensing coil s shown in figure 3 condenses the refrigernt from its

3 The simultor is incorported with some mechnicl components such s compressor, condenser, expnsion system nd n evportor; nd other devices. III. THE WORKING PRINCIPLES The compressor device shown is figure 2 bers the responsibility of compressing the refrigernt so s to increse its temperture nd pressure to enble it move from low temperture region to high temperture region s it is stted in Clusius sttement on the second lw of thermodynmics tht it is impossible for selfcting mchine working in cyclic process unided by ny externl gency, to convey het from body t lower temperture to body t higher temperture [14]. The expnsion component for this opertion is usully grouped into cpillry (orifice) tube or thermosttic expnsion vlve (TEV). In generl note, they hve triple function such s reducing refrigernt temperture in the cooling circuit s it moves to the evportor. It lso determines the refrigernt flow intensity through the cooling circuit nd enbles the compressor to ccomplish its compressing ction by restricting the refrigernt flow. Figure 4 is presenttion of n expnsion unit in the trining simultor Figure 2: Compressor of refrigertion system The condenser or condensing coil s shown in figure 3 condenses the refrigernt from its gseous to liquid stte by cooling process. This is done by getting rid of het extrcted from the interior section of the unit to the outside ir. Thus, receiving the refrigernt s gs from the compressor t high temperture nd pressure nd converts it to liquid t the outlet of the condenser by giving out its het to the surrounding with the id of fn. Figure 4: Expnsion component of refrigertion system. source:[13] The refrigerting effect tkes plce in the evportor which is done by the evportor blower. It sucks the unwnted ir out from the refrigerted re nd blows it through the evportor fins. However s the ir psses through the fins nd gives up its het, it returns to the refrigerted re lot cooler nd drier. A typicl smple of evportor is shown in the figure 5. Figure 5: Evportor of refrigertion system. source:[13] Figure 3: Condenser of refrigertion system source: [13] 245

4 IV. EXPERIMENTATION WITH BASIC REFRIGERATION SYSTEM In order to operte economiclly, the refrigernts re used repetedly. For this reson, the simultor is operted in closed circuit either in TEV or cpillry mode with the support of the four mjor stges; tht is the compression, condenstion, expnsion nd evportion. Figure 6 shows the opertion of the simultor in Skill G lbortory of Niger Delt University. Figure 7: Refrigernt Flow Pth Chrt Cpillry mode of Opertion: Figure 6: Simultor Assembly TEV mode of Opertion: The TEV is used to guge the liquid refrigernt flow entering the evportor t rte equivlent to the mount of refrigernt being evported in the evportor. The vlves regulting this flow s shown in figure 7 provides pressure drop in the system, seprting the high-pressure side of the system from the low-pressure side of the system, llowing the lowpressure refrigernt to bsorb het onto itself. The cpillry tube is designed to lower the cooling liquid pressure which ws rised during the compression process. Thus, the pressure drop on the tube depends on the internl dimeter nd length of the tube, the flow speed, the cooling mteril specific weight nd the friction coefficient between the cooling mteril nd the tube. This is fix control element, which depends on its dimensions nd mteril. V. RESULT PRESENTATION Results obtined re bsed on the opertion mode of the system. Hence two sets of results re presented for ech refrigernt which is used to determine their coefficient of performnce (COP). This will help in the comprison nd justifiction of results to estblish the best stte of refrigertion system nd subsequently the best refrigernt to use for desired operting. Tbles 1 4 is the simultion results for R 134, R 12, R 22 nd R 600 respectively while figures 8 11 shows grphicl plot of results. 246

Evportion Temperture (T5) Condenser Temperture (T3) Coefficient of Performnce Tble 1: Results for Tble 4: Results for R600 Tble 2: Results for R12 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 (TEV (Cp.

5 Evportion Temperture (T5) Condenser Temperture (T3) Coefficient of Performnce Tble 1: Results for Tble 4: Results for R600 Tble 2: Results for R (TEV (Cp. R12 (TEV Stge Number Figure 8: Str-pot of COP versus Stge number Tble 3: Results for R Stge Number (TEV (Cp R12 (TEV R12 (Cp Figure 9: A grph of Condenser Temperture (T 3 ) ginst Stge number Stge Number (TEV) (Cp) 247

6 Temperture Figure 10: Str-pot of Evportion Temperture ginst Stge number Condenstion Temperture (T4) (TEV) (Cp) R12 (TEV) Stge 4 5Number Figure 11: Condenstion Temperture difference with respect to Stge number VI. DISCUSSION OF RESULTS The nlyzed results of the COPs re obtined using the different p h chrts for the refrigernts under study. The corresponding thermodynmic properties of the refrigernts for ech process in the refrigertion system re estimted where vlues re evluted using the equtions below for the derivtion of the COPs in the grphicl plots. COP = COP = COP =...i...ii...iii Estblished results s shown in figure 8 displys the highest COP of 3.23 of the refrigertion system s obtined in R 134 (TEV mode) t stge 3 where compressor nd evportor lod re in off mode with evportor fn operted t low condition. Menwhile, reverse condition of the operting components of the system is observed in R 22 with 0.67 COP (TEV mode) t stge 6. Consequently, the reveled results in figures 9 nd 11 shows tht the R 134 (Cp mode) is cpble of emitting up to 95 cpcity of het from the condenser to the surrounding ir. Similrly, the results in figure 10 displys het bsorption in the evportor. It is obvious tht good refrigerting effect is observed in R 134 (TEV mode), R 12 (Cp mode) nd R 134 (Cp mode) operted in temperture rnge of 60-71, nd respectively. The cpillry mode of opertion for the lst four stges of R 134 experiences drsticlly fll in temperture from This is s result of over loding of the compressor component with ppliction of lod t the evportor. However, s the compressor is put off in stge 8, grdul increse from is seen. One common occurrence observed is the unchnged suction pressure (LP) t stbiliztion point from the TPS simultor. At this stge the cooling effect is observed in the evportor, nd lso long the low pressure pipes in the system. This is the ultimte objective of the refrigerting system. VII. CONCLUSION A close look of results s obtined from the study with the vrying opertionl stges of the different refrigernts leds to the following conclusions: The best condition to determine the highest COP of refrigertor is when the following components such s compressor, evportor lod nd fn re t relxtion condition. R 134 refrigernt is identified s the refrigernt with the highest COP, thus it is considered the best refrigernt for the system. This is lso in-line with the desirble properties for the selection of refrigernts where R 134 is member refrigernt of HFC group considered most environmentl friendly with little or zero level of ozone depleting potentils. Therefore, other refrigernts under the HFC group re considered creditble since they ll shre the sme thermodynmic properties. The R 134 nd R 12 re confirmed s the most suitble refrigernts to be used for domestic nd industril heting purposes respectively from estblished results. Results ttests tht t stbiliztion point, the pressure of the system re good enough for suitble cooling of the system or devices, the refrigernt nd the environment, etc. Therefore, the study is justifible hence the TPS simultor mchine used for the study is replic of the rel refrigertion system for bsic opertion; hence results should be treted s such. 248

7 VIII. ACKNOWLEDGMENT Author sincerely cknowledged Prof. E. A. Ogbonny, former Hed of Deprtment of Mechnicl/Mrine Engineering; Niger Delt University for his unrelenting encourgement. NOMENCLATURE COP Q o W net h T L T H CFC HCFC HFC R E1 Com Ev Coefficient of Performnce Het Extrcted from cold body per cycle Work done per cycle Enthlpy Temperture t lower source Temperture t higher source Chloro Fluoro Crbon Hydro Chloro Fluoro Crbon Hydro Fluoro Crbon Refrigernt Evportor Fn Compressor Evportor IX. REFERENCES [1]. Ajoko, T.J., Refrigertion Systems for University Students. 2015, No 8 Otiotio Rod, Yenego, Byels Stte, Nigeri: Oshe Printing Press/Publictions. [2]. Elumli, P., R. Vijyn, P. S.S. Srinivsn nd C. Chinnrj, An Investigtion on the Performnce Chrcteristics of Environment-Friendly Refrigernt Mixtures in Window Air Conditioner. Middle-Est Journl of Scientific Reserch, (5): p [3]. Allgood, C.C. nd C.C. Lwson, Performnce of R-438A in R-22 refrigertion nd ir conditioning systems [4]. Munsinghe, M. nd K. King, Protecting the ozone lyer. Finnce nd Development, (2): p [5]. Grce, I. nd S. Tssou, Simultion of the performnce of lterntive refrigernts in liquid chillers. Proceedings of the Institution of Mechnicl Engineers, Prt A: Journl of Power nd Energy, (4): p [6]. Jnković, Z., I. Mtić, nd M. Živić, Mthemticl Model of Complete Vpor Compression Refrigertion System with Helicl Coil Evportor Flooded in the Wter. Trnsctions of FAMENA, (SI-1): p [7]. Gullo, P., B. Elmegrd, nd G. Cortell, Energy nd environmentl performnce ssessment of r744 booster. Therml Engineering, : p [8]. A. Pvni, P.M. Reddy, nd G.M.P. Ydv, Performnce Anlysis of Refrigertion System Using Vrious Alterntive Refrigernts. Advnced Engineering nd Applied Sciences: An Interntionl Journl, (1): p [9]. Nglkshmi, K. nd G.M. Ydv, The Design nd Performnce Anlysis of Refrigertion System Using R12 & Refrigernts. Mechnicl engineer t St. Jhons College of Engg &Technology, Yemmignur , A. P, Indi, [10]. Gullo, P., B. Elmegrd, nd G. Cortell, Energy nd environmentl performnce ssessment of R744 booster supermrket refrigertion systems operting in wrm climtes. interntionl journl of refrigertion, : p [11]. Ge, Y. nd S. Tssou, Thermodynmic nlysis of trnscriticl CO 2 booster refrigertion systems in supermrket. Energy Conversion nd Mngement, (4): p [12]. Domnski, P., D. Yshr, nd M. Kim. Performnce of HC nd HFC refrigernts in finned-tube evportor nd its effect on system efficiency. in Nturl Working Fluids Conference, 6th IIR Gustve Lorentzen. Proceedings [13]. Ntionl Universities Commission (NUC), nd Skill 'G' Nigeri Ltd, Science nd Technology Eduction Trining Mnul on Air-Conditioning nd Refrigertion Trining Systems for Higher Eductionl Institution (HEIs) nd Technicl Voctionl Eductionl Trining (TVET). 2015, Abuj - Nigeri: Scientific Eductionl Systems (SES). [14]. Rjput, R., Therml engineering. 2010: Lxmi Publictions. 249

Performance evaluation of displacement ventilation system combined with a novel evaporative cooled ceiling for a typical office in the city of Beirut

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