(Daily Question) Coal-to-Oil and Olefins Forum, 3/23/2018

A cooling cycle in which two or more refrigeration cycles are combined together according to a certain structure to perform cooling.

A cascade refrigeration machine typically consists of two separate refrigeration systems, referred to as the high-temperature stage and the low-temperature stage. A medium-temperature refrigerant is used in the high-temperature section, while a low-temperature refrigerant is used in the low-temperature section. In high-temperature sections of the system, the evaporation of the refrigerant is used to cause the refrigerant in the low-temperature sections to condense. A condensing evaporator connects these two sections; it functions as both an evaporator in the high-temperature section and a condenser in the low-temperature section. The refrigerant in the low-temperature section absorbs heat from the object to be cooled inside the evaporator (i.e., generates cooling capacity), and transfers this heat to the refrigerant in the high-temperature section; thereafter, the refrigerant in the high-temperature section transfers the heat to the cooling medium (water or air).

A cooling cycle in which two or more refrigeration cycles are combined together according to a certain structure to perform cooling.

Serial operation using two or more refrigerants is employed, where the condensation effect produced by one refrigerant is used to condense another refrigerant with a lower boiling point; the cooling effect generated by that refrigerant is then used to cool yet another refrigerant with an even lower boiling point. In this manner, liquefaction occurs step by step, allowing very low temperatures to be achieved – this is known as cascade refrigeration

A cascade refrigeration cycle is a method that divides the overall temperature difference into two or more sections; an appropriate refrigerant cycle is selected for each section based on its temperature range, and these cycles are then combined together. The cooling capacity of the higher temperature stage is used to handle the condensation load of the lower temperature stages, thereby achieving a lower cooling temperature. Cascade refrigeration is a special form of vapor compression refrigeration; it typically consists of two to three independent vapor compression refrigeration cycles operating at different temperature ranges. Taking a two-stage cascade refrigeration cycle as an example, it is made up of a high-temperature stage and a low-temperature stage – a medium-temperature refrigerant is used in the high-temperature stage, while a low-temperature refrigerant is used in the low-temperature stage, thus creating a cycle in which two single-stage compression refrigeration systems operate in cascade. A condensation-evaporation evaporator is used to connect the two-stage system; in this evaporator, the medium-temperature refrigerant from the high-temperature stage evaporates to provide cooling, causing the low-temperature refrigerant to release heat. After exchanging heat with the evaporated medium-temperature refrigerant, it is condensed back into a liquid state. The medium-temperature refrigerant vapor exiting the condensing evaporator carries away the heat of condensation of the low-temperature refrigerant, and this heat is transferred to the surrounding environment through the high-temperature refrigeration cycle. The low-temperature refrigerant liquid coming out of the condensing evaporator passes through a low-temperature throttle valve to have its pressure reduced, and then enters the evaporator where it absorbs heat from the substance to be cooled, thereby evaporating and providing the desired low temperature.

By operating two or more refrigerants in series, using the condensation effect produced by one refrigerant to condense another with a lower boiling point, and then using the cooling effect generated by that refrigerant to cool yet another refrigerant with an even lower boiling point, liquefaction can be achieved step by step, allowing very low temperatures to be reached; this is known as cascade refrigeration!

Serial operation using two or more refrigerants is employed, where the condensation effect produced by one refrigerant is used to condense another refrigerant with a lower boiling point; the cooling effect generated by that refrigerant is then used to cool yet another refrigerant with an even lower boiling point. In this manner, liquefaction occurs step by step, allowing very low temperatures to be achieved – this is known as cascade refrigeration

By operating two or more refrigerants in series, using the condensation effect produced by one refrigerant to condense another with a lower boiling point, and then using the cooling effect generated by that refrigerant to cool yet another refrigerant with an even lower boiling point, liquefaction can be achieved step by step, allowing very low temperatures to be reached; this is known as cascade refrigeration!

Cascade refrigeration: It usually consists of two separate refrigeration systems, referred to as the high-temperature stage and the low-temperature stage. A medium-temperature refrigerant is used in the high-temperature section, while a low-temperature refrigerant is used in the low-temperature section. In high-temperature sections of the system, the evaporation of the refrigerant is used to cause the refrigerant in the low-temperature sections to condense. A condensing evaporator connects these two sections; it functions as both an evaporator in the high-temperature section and a condenser in the low-temperature section. The refrigerant in the low-temperature section absorbs heat from the object to be cooled inside the evaporator (i.e., generates cooling capacity), and transfers this heat to the refrigerant in the high-temperature section; thereafter, the refrigerant in the high-temperature section transfers the heat to the cooling medium (water or air).