A simple analysis of the differences between chillers and heat pumps

As is well known, the chiller unit, also known as the refrigeration unit, mainly cools and cools the equipment. With the compressor as the core, heat is transferred from the low-temperature evaporator end to the high-temperature condenser end through a reasonable matching of the evaporator, condenser, and corresponding throttling capillaries, thereby achieving effective cooling of the evaporator end. A heat pump machine refers to a unit that can produce both cold water and hot water. He has a switching function, which can switch to a chiller unit in summer and a hot water unit in winter to produce hot water.

So, what are the specific differences between the two devices? To sum up, they have different components, structures, and purposes.

The chiller unit only has a single refrigeration and cooling function, treating the environment as a high-temperature heat source. The main components of its system include a compressor, condenser, throttling component, and evaporator, and the refrigerant flows unidirectionally within the evaporator and condenser. The heat exchange area of the evaporator and condenser of the chiller unit can be appropriately reduced, and the compressor capacity can also be appropriately selected to be smaller. Balance can be achieved by increasing the air volume of the condensing and evaporating fans.

The heat pump unit needs to switch between cooling and heating modes. In addition to the compressor, condenser, throttling component, and evaporator, there is also a very important component in the system pipeline, the four-way directional valve. The system executes the conversion of cooling and heating modes of the heat pump unit through the switching of the four-way directional valve. In the short period of time during the mode switching of the heat pump unit, there will be a lot of liquid refrigerant flowing into the compressor through the four-way directional valve. In order to prevent liquid refrigerant from directly returning to the compressor without causing liquid hammer, it is necessary to add a gas-liquid separator of appropriate size on the suction pipeline of the compressor. The refrigerant flow required for the heating execution of the unit is less than the refrigerant flow required for the refrigeration execution. Excessive refrigerant needs to be stored in a dedicated storage tank, which is set in the heat pump unit system.

When the interaction between the chiller or heat pump unit and the surrounding environment in terms of energy is to absorb heat from a low-temperature heat source and then release heat to a high-temperature heat source, its purpose is to obtain high-temperature heating, that is, to release heat to the high-temperature part. If the purpose of the heat pump is to obtain low-temperature cooling, that is, to absorb heat from a low-temperature heat source, then it is a refrigeration chiller.

So, usually heat pump water heaters use the environment as a low-temperature heat source, while chillers use the environment as a high-temperature heat source. The principle of a heat pump unit and a chiller unit is basically the same. A heat pump is a refrigeration system that uses the heat released by a condenser or other components to provide heat. In principle, any cycle that can be used as a chiller can be used as a heat pump cycle, and any analysis method used for chillers can be used to analyze heat pumps.

Source: Coolingstyle