## GATE ME solved Questions on Second Law of Thermodynamics

Question #1

A heat pump absorbs 10 kW of heat from outside environment at 250 K while absorbing 15 kW of work. It delivers the heat to a room that must be kept warm at 300K. The Coefficient of Performance (COP) of the heat pump is ___________.

[GATE 2017 Set 1, 1 mark]

Question #2

The heat removal rate from a refrigerated space and the power input to the compressor are 7.2 kW and 1.8 kW, respectively. The coefficient of performance (COP) of the refrigerator is ______

[GATE 2016 Set 2, 1 mark]

Question #3

A reversible cycle receives 40 kJ of heat from one heat source at a temperature of 127 oC and 37 kJ from another heat source at 97 oC. The heat rejected (in kJ) to the heat sink at 47 oC is __________

[GATE 2016 Set 2, 2 marks]

Question #4

A Carnot engine (CE-1) works between two temperature reservoirs A and B, where TA = 900 K and TB = 500 K. A second Carnot engine (CE-2) works between temperature reservoirs B and C, where TC = 300 K. In each cycle of CE-1 and CE-2, all the heat rejected by CE-1 to reservoir B is used by CE-2. For one cycle of operation, if the net Q absorbed by CE-1 from reservoir A is 150 MJ, the net heat rejected to reservoir C by CE-2 (in MJ) is ______________

[GATE 2015 Set 1, 1 mark]

Question #5

The COP of a Carnot heat pump operating between 6 °C and 37 °C is ___________

[GATE 2015 Set 2, 1 mark]

Question #6

A reversed Carnot cycle refrigerator maintains a temperature of −5° C. The ambient air temperature is 35°C. The heat gained by the refrigerator at a continuous rate is 2.5 kJ/s. The power (in watt) required to pump this heat out continuously is _______

[GATE 2014 Set 4, 1 mark]

Question #7

A reversible heat engine receives 2 kJ of heat from a reservoir at 1000 K and a certain amount of heat from a reservoir at 800 K. It rejects 1 kJ of heat to a reservoir at 400 K. The net work output (in kJ) of the cycle is
(A) 0.8

(B) 1.0

(C) 1.4

(D) 2.0

[GATE 2014 Set 1, 1 mark]

Question #8

An irreversible heat engine extracts heat from a high temperature source at a rate of 100 kW and rejects heat to a sink at a rate of 50 kW. The entire work output of the heat engine is used to drive a reversible heat pump operating between a set of independent isothermal heat reserviors at 17 oC and 75 oC.The rate (in kW) at which the heat pump delivers heat to its high temprature sink iss

(A) 50

(B) 250

(C) 300

(D) 360

[GATE 2009, 2 marks]

Question #9
A heat transformer is a device that transfers a part of the heat, supplied to it at an intermediate temperature, to a high temperature reservoir while rejecting the remaining part to a low temperature heat sink. In such a heat transformer, 100 kJ of heat is supplied at 350 K. The maximum amount of heat in kJ that can be transferred to 400 K, when the rest is rejected to a heat sink at 300 K is

(A) 12.50

(B) 14.29

(C) 33.33

(D) 57.14

[GATE 2007, 2 marks]

Question #10

A Solar collector receiving solar radiation at the rate of 0.6kW/m2 transforms it to the internal energy of a fluid at an overall efficiency of 50 %. The fluid heated to 350 K is used to run a heat engine which rejects heat at 313 K.If the heat engine is to deliver  2.5 kW power, then the minimum area of the solar collector required would be

(A) 8.33 m2

(B) 16.66 m2

(C) 39.68 m2

(D) 79.36 m2

[GATE 2004, 2 marks]

Practice other topics from thermodynamics:

Basics of Thermodynamics

Heat and work

First law of thermodynamics