Mr Slim Air Conditioner. Thermodynamic Heat Pump Cycles or Refrigeration Cycles. 

Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pumps and refrigerators. A heat pump is a machine or device that moves heat from one location (the 'source') at a lower temperature to another location (the 'sink' or 'heat sink') at a higher temperature using mechanical work or a high-temperature heat source. Thus a heat pump may be thought of a "heater" if the objective is to warm the heat sink (as when warming the inside of a home on a cold day), or a "refrigerator" if the objective is to cool the heat source (as in the normal operation of a freezer). In either case, the operating principles are identical. Heat is moved from a cold place to a warm place.

According to the second law of thermodynamics heat cannot spontaneously flow from a colder location to a hotter area; work is required to achieve this.  An air conditioner requires work to cool a living space, moving heat from the cooler interior (the heat source) to the warmer outdoors (the heat sink). Similarly, a refrigerator moves heat from inside the cold icebox (the heat source) to the warmer room-temperature air of the kitchen (the heat sink). The operating principle of the refrigeration cycle was described mathematically by Sadi Carnot in 1824 as a heat engine. A heat pump can be thought of as heat engine which is operating in reverse. Heat pump and refrigeration cycles can be classified as vapor compression, vapor absorption, gas cycle, or Stirling cycle types.

A heat pump may be compared with a CHP unit, in that for a condensing steam plant, as it switches to produced heat, then electrical power is lost or becomes unavailable, just as the power used in a heat pump becomes unavailable. Typically for every unit of power lost, then about 6 units of heat are made available at about 90oC. Thus CHP has an effective COP compared to a heat pump of 6.