A heat engine having an efficiency of 70% is used to drive a refrigerator having a coefficient of performance of 5. The energy absorbed from the low-temperature reservoir by the refrigerator for each kJ of energy absorbed from the high-temperature source by the engine is ________ A. 0.14 kJ B. 0.71

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 reservoirs at 17 C and

A vapor absorption refrigeration system is a heat pump with three thermal reservoirs as shown in the figure. A refrigeration effect of 100 W is required at 250 K when the heat source available is at 400 K. Heat rejection occurs at 300 K. The minimum value of heat required (in W) is A. 167 B. 100 C.

A Carnot engine (CE-1) works between two temperature reservoirs A and B, where T1=900K and T2=500K. A second Carnot engine (CE-2) works between temperature reservoirs B and C, where T3=300K. 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 o

An industrial heat pump operates between the temperatures of 27∘C and −13∘C. The rates of heat addition and heat rejections are 750 W and 1000 W, respectively. The COP for the heat pump is A. 7.5 B. 6.5 C. 4.0 D. 3.0

A cyclic heat engine does 50 kJ of work per cycle. If the efficiency of the heat engine is 75%, then heat rejected per cycle is _____ A. 16 2/3 kJ B. 33 1/3 kJ C. 37 1/2 kJ D. 66 2/3 kJ

A cyclic device operates between three thermal reservoirs, as shown in the figure. Heat is transferred to/from the cyclic device. It is assumed that heat transfer between each thermal reservoir and the cyclic device takes place across negligible temperature differences. Interactions between the cycl

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 h

What is Efficiency? What is COP? What is the difference between COP and Efficiency? When to use what?

A Stirling cycle and a Carnot cycle operating between 50 C and 350 C. Their efficiencies are ηs and ηc respectively. In this case, which of the following statements is true? A. ηs > ηc B. ηs = ηc C. ηs < ηc D. The sign of (ηs - ηc) depends on the working fluid used

A Carnot cycle refrigerator operates between 250 K and 300 K. Its coefficient of performance is ___ A. 6.0 B. 5.0 C. 1.2 D. 0.8

Consider the following two processes; (I) A heat source at 1200 K loses 2500 kJ of heat to a sink at 800 K (II) A heat source at 800 K loses 2000 kJ of heat to a sink at 500 K. Which of the following statements is true? A. Process I is more irreversible than process II B. Process II is more irreve