Chapter 5, Problem 5.108EP

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A refrigerator cycle uses refrigerant R-134a and operates between a low-side pressure of 1.5 Bar and high side of 10 Bar. The power input to the compressor 1.88 Kw. find the refrigerant mass flow rate, condensing heat load, and COP of this machine

A refrigerator in a meat warehouse must keep a low temperature of -20°C and the outside temperature is 25°C. Ammonia is used as the refrigerant which must remove 10 kW from the cold space. Compute for the flow rate of the ammonia needed assuming a standard vapor compression refrigeration cycle with a condenser at 25°C. Find the enthalpy of the stream exiting the evaporator, condenser, and throttling (expansion) valve.

Find the COP of heat pump operating between 300 K and 600K temperature. If the same temperature ranges are used in heat engine, find the efficiency.

A refrigeration system has a COP of 4.The compressor power is 30 kw.Find the mass of ice produced by the system in 16 hrs from 30C to ice at-6 C.if miscellaneous losses is 35%.

Q3/ A refrigeration unit of 20 T.R uses R-12 as a refrigerant and works between evaporating and condensing (10 degree) temperature of -20 °C and 37 °C. The vapor leaves the evaporator saturated and the liquid leaves the condenser saturated also. Find out the change of; (a) Mass flow rate of refrigerant, (b) Power consumed, (c) Volumetric efficiency, and (d) Piston displacement in the following to cases (i) The evaporation temperature is decreased to -27 °C due to a change of product while the condensing temperature is still constant, (ii) The condensing temperature is increased to 45 °C due to a change of outside conditions while the evaporating temperature is still constant at -20 °C.

A computer lab filled with 20 computers and 15 students is cooled by an air conditioningunit on a day where it is 90 oF outside. The room temperature is 72 oF. Assume an averagestudent generate 90 W of heat and each computer generates 150 W of heat. If the COP ofthe air conditioner is 2.5, what power input is required, in kW? If the air conditioneroperated at its maximum coefficient of performance, what power input would be required?

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Heat is transferred to a heat engine from a fumace at a rate of 120KW. If the rate of waste heat rejection to a nearby river is 50000W. Find the net Power output and the thermal efficiency for this heat engine.