SHASHANK VASHISTHAME10401206589ASSIGNMENT 1 SEM7Th C-2Q.1(a) Expa!" #h$ a%#&a 'ap(&) %(*p)$++!(" %,%$.Ans: The actual vapour compression cycle difers from the theoretical vapour compression cycle in many ways. Some of which are unavoidable and causes losses.The main deviation between theoretical and actual cycle are in followa:a. The vapour refrigerant leaving the evaporator is in superheated state.b. The compression of refrigerant is neither isentropic nor polytropic.c. The liquid refrigerant before entering the expansion valve is subcooled in the condenser.d. The pressure drop in the evaporator and condenser.Process !"!#These processes show the $ow of refrigerant in the evaporator. Pointrepresent entry and point # represent exit of refrigerant from evaporator. The superheating of refrigerant %vapour&from "!# is due toa. Automatic control of expansion valve.b. Pic'ing up of large amount of heat from evaporator through pipes located within the cooled space.c. Pic'ing up heat from the suction pipe.The superheating is also causes increase in the required displacement of compressor and load on the compressor and condenser.Process #!(!)!*!+!,This process is represents the $ow of refrigerant through the compressor.a. At point # refrigerant enters the compressor through suction pipe.b. At point ( the pressure falls due to frictional resistance to $ow.c. At point ) the temp is raised up due to coming in contact of the walls of compressor cylinder.d. Actual compression is shown by )!*. This is due to the heat transfer of between cylinder wall - vapour refrigerant.e. There is cooling efect in process *!+. This heating and cooling efect is ta'e place at constant pressure..ue to frictional resistance of $ow there is pressure drop.Process ,!/!0!This process represent $ow of refrigerant through condenser.a. Process,!/ represents the cooling of superheated vapour refrigerant to dry saturated state.b. Process /!0 represents the removal of latent heat which changes the dre saturated refrigerant into liquid refrigerant.c. Process 0! represent subcooling of liquid refrigerant in the condenser before passing it through the expansion valve. This increases the refrigerant efect per 'g of refrigerant $ow. 1educes the volume of refrigerant partially evaporated the liquid refrigerant while passing through the expansion valve.Process !This represents the expansion of subcooled liquid refrigerant by throttling from the condenser pressure to evaporator pressure.Q.2(b) A vapour compression refrigerator uses R-12 as refrigerant and the liquid evaporates in theevaporator at -15

!. "he temperature of this refrigerant at the deliver# from the compressor is15

! $hen the vapour is condensed at 1o!. %ind the !.&.' if (i) there is no under cooling (ii) the liquid is cooled b# 5

! before e(pension b# throttling. "a)e specific heat at constant pressure for the superheated vapour as .*+ ),-)g . and that for liquid as ./+ ),-)g .. "he other properties of refrigerant are as follo$s0Ans: 2iven: T3T(3!) 43"), 'T"3) 43",, ' T"530 43",# '4pv30.*( '67'g '4pl30./( '67'g ' hf3"".# '67'g hf#53().( '67'gh53,0.,, '67'g h"53/.+* '67'g Sf30.0/0( '67'g 'Sf#30.+)0 '67'g ' Sg30.+0) '67'g ' S"530.*/" '67'g 'A. 489::;49"3 >"5 B 4pv%Tact E Tsat&>"3 >"5 B 4pv%T" E T"5&>"3 /.+* B 0.*(C)>"3 /(./* '67'g4.8.P3 %> E >f#5&7%>" E >& 3 /."+ ansG.H.489::;49919 ;S A< ?