R32 Energy Analysis Of Heat Pumps

In the heat pump cycle, Q0 kcal/h of heat is obtained from the low-temperature heat source (outdoor air or circulating water, whose temperature is higher than the evaporation temperature t0), mechanical work ALkcal/h is consumed, and Q1 kcal/h of heat is supplied to the high-temperature heat source (indoor heating system). The relationship between these heats conforms to the first law of thermodynamics, that is, Q1=Q0+AL kcal/h. If the heat pump device is not used, and the heat converted from mechanical work (or the high-temperature heat source is directly heated by electrical energy), the heat obtained is ALkcal/h. After the heat pump device is used, the high-temperature heat source (heating system) obtains more heat: Q1-AL=Q0 kcal/h. This heat is obtained from a low-temperature heat source. If a heat pump device is not used, this heat cannot be obtained. Therefore, the use of a heat pump device can save fuel and utilize waste heat. The working cycle of a heat pump is exactly the opposite of that of a heat engine. A heat engine uses the energy of a high-temperature heat source to generate mechanical work, while a heat pump transfers the heat of a low-temperature heat source to a high-temperature object by consuming mechanical work. A heat pump has two identical heat source temperatures, and the relationship between them is: φ=Q1╱AL=(Q0+AL)╱AL=ε+1, where ε is the refrigeration coefficient of the refrigerator. It can be seen from this that the minimum value of the heat conversion coefficient is φ=1. In this limit, ε=0, Q0=0, that is, no heat is absorbed from the low-temperature heat source.