Question

Which of the following is a secondary refrigerant?

• A. \(\text{NH$_3$}\)
• B. \(\text{H$_2$O}\)
• C. \(\text{CO$_2$}\)
• D. \(R_{12}\)

Hint:

Secondary refrigerants like water help transfer cooling energy efficiently but do not undergo phase changes in the cooling cycle.

Answer 1

The Correct Option is B

Step 1: Understanding primary and secondary refrigerants.
- Primary refrigerants change phase to absorb heat and are directly responsible for cooling (e.g., NH$_3$, CO$_2$, R$_{12}$).
- Secondary refrigerants are used to transfer the heat absorbed by primary refrigerants without undergoing phase change themselves.

Step 2: Explanation of incorrect options.
- (A) NH$_3$ (Ammonia): A primary refrigerant used in refrigeration systems.
- (C) CO$_2$ (Carbon dioxide): Another primary refrigerant commonly used in refrigeration systems.
- (D) R$_{12}$ (Dichlorodifluoromethane): A now-outdated primary refrigerant, formerly used in refrigeration systems.

Step 3: Selecting the correct option.
Since H$_2$O (water) is commonly used as a secondary refrigerant in systems such as chilled water systems, the correct answer is (B) H$_2$O.