Question

a refrigerator uses refrigerant 134a as a working fluid and operates on the vapour -compression refrigiration cycle.the evaporator is maintained at -10⁰C and the refrigirant is a dry saturated vapour as it leaves the evaporator. the compressor has an efficiency of 80%.the conditions at the outlet of the condensor are 30⁰C and 9 bar.

1-if the mass flow rate of the refrigerant is 0,08kg/s workout the rate of heat removal from the refrigerant space.the power input to the cpmpressor and the COP of the refrigerator.sketch all state points and the cycle on the p-h diagram for the refrigerant

2state four desurable properties of a refrigerant

Answer 1

Page ne Anueu Given woy king Pluid and erigerant 134 a A ues vnрои- compresion неtiganation cyoe. the ороates on -10 c maintained Evaporator is at Comprenor ficieny s0% 30°C&9 bar Condensoy of the are at tho outlet The conditions ka/sec. m0.03 Mau Plow yote the power input to determina is The objecti ve Prom the tha CoP and дmaвзя Compresior points and the on the all state also sketch And qerant the foY dingram Tde al 2S 3 abar 3a Actual -10°c Fom steaum tables; h 244. 52 k3kg

ne 2 목리/ 오7 5 Than hhCp. CATt 3a 01 6 Sat 30 06-8 I499 hahu93.4 5 followos The Rate of heat emeval is calculated as the valuas in above eation, we yet ysubstitating G는 0,01[244 52-6 93. 45 -0.08 12.086 w the diogram ; 1-25 PTOce is 3sentropic PTocem 5,S2 o.9377 CoTes ponding ło P29 ban rom super heated steam table, get intepolation) Sao.93 ue - 275

Porge ne 3 2S egiation we Substituting valuen akove - 244. 52 0.8257 h 2452 h2-24452. - 31.18 O 8 hg-24452 38.975 h283.45 Pollows comprenor iscal culatad . Power input to the Power input Pin 1345- 0.08 244.5 0.0 3. 475 - 3. i18 keo ir Calculatad COP is CoP 2 086 3 8 Cop 3. 88

Page 2. Dile propeties of Refrigant Vapor denity Small size of compressors and othe of To enable the sage have vapor density Smaller sheuld Tefrigeroaut the equipment Eathaloy ofVaporization the maximum using Yefrigation Tehrigerand haat absoyption .to ensure J high enthalpy of porization, have a should a Thermal Conductivty Candeuctivity Dsing vefigorant and evoporation, the thomal condensation high transfer Paster haat fox sheuld of be ieleic Strenath metor windinga angaments cooled byYefrigeranti vaper the n hormetic auro the Suction Yalve of on ts way to retrigorant dielectbric strngth kerm eically the compresax. So korco, the se aled compresor uni *Critical To hawe a bToad iso themal ererg of sans fer critical temperature above th the eFrigerant should have a Condensing temperature