Application and composition principle of condenser

A condenser is a component of a refrigeration system, belonging to a type of heat exchanger. It can convert gas or vapor into liquid and quickly transfer the heat in the pipes to the air near the pipes. The working process of the condenser is an exothermic process, so the temperature of the condenser is relatively high.

Power plants use many condensers to condense the steam discharged from turbines. Condensers are used in refrigeration plants to condense refrigeration vapors such as ammonia and fluorocarbons. Condensers are used in the petrochemical industry to condense hydrocarbons and other chemical vapors. The device that converts vapor into liquid during the distillation process is also known as a condenser. All condensers operate by taking away the heat from gases or vapors.

Gas passes through a long tube (usually coiled into a solenoid) to dissipate heat into the surrounding air. Metals such as copper have strong thermal conductivity and are commonly used for transporting steam. To improve the efficiency of the condenser, heat dissipation fins with excellent thermal conductivity are often attached to the pipes, increasing the heat dissipation area to accelerate heat dissipation, and using fans to accelerate air convection and remove heat.

In the circulation system of the refrigeration machine, the compressor sucks in low-temperature and low-pressure refrigerant vapor from the evaporator, which is adiabatically compressed by the compressor into high-temperature and high-pressure superheated vapor, and then pressed into the condenser for constant pressure cooling, releasing heat to the cooling medium, and then cooled into supercooled liquid refrigerant. The liquid refrigerant is adiabatically throttled by the expansion valve to become a low-pressure liquid refrigerant, which evaporates and absorbs heat from the air conditioning circulating water (air) in the evaporator, thereby cooling the air conditioning circulating water to achieve the purpose of refrigeration. The low-pressure refrigerant flowing out is sucked into the compressor and works in this cycle.

A single-stage vapor compression refrigeration system consists of four basic components: a refrigeration compressor, a condenser, a throttle valve, and an evaporator, which are connected in sequence by pipelines to form a closed system. The refrigerant continuously circulates in the system, undergoes state changes, and exchanges heat with the outside world.

In a refrigeration system, the evaporator, condenser, compressor, and throttle valve are the four essential components, among which the evaporator is the equipment that delivers cold. The refrigerant absorbs heat from the cooled object to achieve refrigeration. The compressor is the heart, which plays a role in inhaling, compressing, and transporting refrigerant vapor. The condenser is a device that releases heat, transferring the heat absorbed in the evaporator along with the heat converted by the compressor to the cooling medium for removal. The throttle valve has a throttling and pressure reducing effect on the refrigerant, while controlling and regulating the amount of refrigerant liquid flowing into the evaporator, and dividing the system into two parts: the high-pressure side and the low-pressure side. In actual refrigeration systems, in addition to the four major components mentioned above, there are often auxiliary equipment such as solenoid valves, distributors, dryers, collectors, fusible plugs, pressure controllers, etc., which are set up to improve the economy, reliability, and safety of operation.

Air conditioning units can be divided into two types based on their condensation form: water-cooled and air-cooled. Depending on their usage purpose, they can be divided into single cooling and cooling/heating types. Regardless of which type of unit is used, it is composed of the following main components.

The necessity of a condenser is based on the second law of thermodynamics - according to the second law of thermodynamics, the spontaneous flow direction of thermal energy inside a closed system is unidirectional, that is, it can only flow from high heat to low heat, and in the microscopic world, it manifests as the microscopic particles carrying thermal energy can only change from order to disorder. So, while a heat engine has energy input to do work, there must also be energy release downstream, so that there is a difference in thermal energy between upstream and downstream, and the flow of thermal energy becomes possible, and the cycle continues.

So, if you want the load to do work again, you must first release the heat energy that has not been completely released, and then a condenser is needed. If the surrounding heat energy is higher than the temperature in the condenser, artificial work (usually using a compressor) must be done to cool the condenser. The condensed fluid returns to a highly ordered and low thermal state, allowing it to perform work again.

The selection of a condenser includes the choice of form and model, as well as determining the flow rate and resistance of the cooling water or air flowing through the condenser. The selection of condenser type should consider the local water source, water temperature, climate conditions, as well as the total cooling capacity of the refrigeration system and the layout requirements of the refrigeration room. On the premise of determining the type of condenser, the heat transfer area of the condenser is calculated based on the condensation load and the heat load per unit area of the condenser, in order to select the specific type of condenser.