Chapter 5, Problem 5.42CU

Figure P6.22 provides the T-s diagram of a Carnot refrigeration cycle for which the substance is Refrigerant 134a. Determine the coefficient of performance.

At steady state, a refrigeration cycle removes 800 kJ/min of energy by heat transfer from acold space maintained at -15o C and discharges energy by heat transfer to its surroundings at20o C. If the coefficient of performance of the actual cycle is 80 percent of that of areversible refrigeration cycle (ideal) operating between thermal reservoirs at these twotemperatures (β = 0.80 βmax), determine:a) Coefficient of performance;b) Power input to the cycle, in kW;c) Heat rejected to the surroundings.Draw sketch and show all calculations.

An air conditioner is a device used to cool the inside of a home. It is, in essence, a refrigerator in which mechanical work is done and heat removed from the (cooler) inside and rejected to the (warmer) outside. A home air conditioner operating on a reversible Carnot cycle between the inside, absolute temperature T2, and the outside, absolute tempera- ture T1 > T2, consumes P joules/sec from the power lines when operating continuously. (a) In one second, the air conditioner absorbs Q2 joules from the house and rejects Q1 joules outdoors. Develop a formula for the efficiency ratio Q2/P in terms of T1 and T2. (b) Heat leakage into the house follows Newton's law Q = A(T, – T2). Develop a formula for T, in terms of T1, P, and A for continuous operation of the air conditioner under constant outside temperature T and uniform (in space) inside temperature T2. (c) The air conditioner is controlled by the usual on-off thermostat and it is observed that when the thermostat set at 20°C and an…