NH3/CO2/Glycol Evaporator for Logistics Warehouses

NH3/CO2/glycol evaporators are components of a refrigeration system commonly used in logistics warehouses where both positive and negative temperature refrigeration needs to be met. This system utilizes a combination of ammonia (NH3), carbon dioxide (CO2), and glycol as refrigerants, each serving specific purposes within the system.

Components and Functionality:

Ammonia (NH3):

NH3 is used as the primary refrigerant in this system due to its excellent thermodynamic properties and efficiency.

It is typically used in the low-temperature evaporators (-20°C to -40°C) for freezing applications.

Carbon Dioxide (CO2):

CO2 is used as a secondary refrigerant, mainly in the medium-temperature evaporators (0°C to -20°C).

It is often circulated in a secondary loop, where it absorbs heat from the refrigerated space and then transfers it to the NH3 refrigeration system.

Glycol:

Glycol is used as an antifreeze solution in the system, especially in areas where low temperatures are required.

It helps maintain the desired temperatures and prevents freezing within the system.

Positive Temperature Applications:

Medium-Temperature Evaporators (0°C to -20°C):

CO2 is circulated through the medium-temperature evaporators, absorbing heat from the refrigerated space.

This heat is then transferred to the NH3 system via a heat exchanger, where it is ultimately rejected outside the warehouse.

Glycol Applications:

Glycol can be used in positive temperature applications, such as chilled storage areas or refrigerated docks.

It helps maintain temperatures above freezing and prevents frost build-up.

Negative Temperature Applications:

Low-Temperature Evaporators (-20°C to -40°C):

NH3 serves as the primary refrigerant in low-temperature applications, such as blast freezers or deep freeze storage.

It absorbs heat from the freezer space, causing the evaporation of NH3 and lowering the temperature.

Defrosting:

In negative temperature applications, periodic defrost cycles may be necessary to remove ice build-up on the evaporator coils.

This can be accomplished through various methods, including hot gas defrost, electric defrost, or even using the glycol solution.