The refrigerant condenser
The refrigerant condenser is an important component in refrigeration and air conditioning systems. Its main task is to transfer the heat absorbed by the system to its surroundings. The condenser adjusts and regulates the condensation pressure in the refrigeration cycle. Depending on how much or how little heat is released to the surroundings, the condensation pressure of the refrigeration and air conditioning system is established on the high-pressure side.
Heat exchange takes place through a heat exchanger. From an energy perspective, it is beneficial to utilize the waste heat here.
- Keywords: heat recovery or heat pump -
Heat transport within the refrigeration and air conditioning system is carried out by a refrigerant.
- The refrigerant -
In the condenser, the refrigerant is transformed from a gaseous to a liquid state through heat dissipation. There are thermodynamically three zones in the condenser:
- De-superheating zone
- Condensing zone
- Subcooling zone
In the condensing zone, one could also speak of condensation, which is why the refrigerant condenser is also referred to as a condenser.
The condenser is available in different operating modes and designs. Depending on the on-site installation conditions, the capacity of the refrigeration system, and the application, an individual assessment and appropriate selection of the design are necessary for each refrigeration and air conditioning system.
Air-cooled condensers with finned heat exchangers are the most common.
They consist of a block with a tube system to which fins are attached or pushed onto. The tubes are usually internally ribbed. All of this increases the heat transfer surface area and ensures smaller dimensions of the condenser itself. Heat dissipation to the ambient air is achieved through dry heat exchange surfaces using fans or natural convection.
Air-cooled condensers are available in the following configurations:
- Directly in the ventilation duct
Hybrid condensers are used to handle peak loads. They spray water onto the heat transfer surfaces, which evaporates. As a result, the condenser's capacity increases significantly, and the component can be made smaller in size. The term "hybrid" comes from the fact that the condenser can be operated in both dry and wet conditions. Depending on the water quality and source, water treatment and disinfection may need to be considered. Additionally, it is necessary to check if the 42nd Federal Immission Control Ordinance (42. BImSchV) applies to evaporative cooling systems, cooling towers, and wet separators.
The principle of the evaporative condenser is similar to that of the hybrid condenser. However, the device's construction is slightly different. Water is directed through additional baffles, cooling the incoming ambient air significantly.
The temperature drop is greater when the surrounding air is drier. The wet-bulb temperature is the theoretically achievable limit of the intake temperature and is often referred to as the cooling limit temperature. The cooled air is then directed through the heat exchange surface of the condenser, where the refrigerant circulates.
Water treatment and disinfection must be considered for evaporative condensers.
Depending on the design, water is collected in trays, circulates multiple times over the fins, and evaporates in the process. As with the hybrid condenser, compliance with the 42nd BImSchV in EU is required for an evaporative condenser.
The most common types are shell-and-tube or shell-and-coil condensers. The vessel contains tubes through which the cooling medium flows, while the circulating refrigerant releases its heat to the water and condenses in the shell space.
The following can be used as cooling media on the waterside:
- City water
- Well or river water
- Loop-connected systems