Question

Determine the condensing and evaporating temperatures for your heat pump. Please note that the

condensing temperature should be a few degrees higher than the hot water temperature, while the

evaporating temperature should be a few degrees lowered than the river water temperature. Please

provide a justification for your choice.

• Select a refrigerant and provide a justification of your selection. You should consider their ozone depletion

potential, global warming potential, toxicity, flammability, cost, etc.

Design a two-stage heat pump. You can select a cycle layout from those that we covered in lectures.

Alternatively, you can design your own cycle layout.

• You should sketch the schematic diagram of your design, and the corresponding pressure-enthalpy and

temperature-entropy diagrams.

• Find the thermophysical properties and conduct a cycle analysis. Show all the equations and calculations

including COP, mass flowrate of refrigerant, power consumptions of compressors, heat extraction rate

from river, etc.

Calculate the minimum mass flow rate of water that you need to extract from the river to provide the

required heat while maintaining the return temperature above 4 °C.

• Select the type of compressor, expansion device, heat exchangers for the evaporator and condenser, and

provide your justification.