RSES System Design & Load Calculation 1 — Questions and Answers
Question 1: What is the primary purpose of performing a refrigeration load calculation before system design?
- To determine the correct refrigerant type to use
- To properly size the refrigeration equipment for the application (Correct answer)
- To select the appropriate compressor oil viscosity
- To establish the required electrical service amperage
Correct answer: To properly size the refrigeration equipment for the application
Load calculations determine the total heat that must be removed, which dictates the proper sizing of condensing units, evaporators, and related components.
Question 2: Which of the following is the standard unit used to express refrigeration capacity in the United States?
- BTU
- Ton of refrigeration (Correct answer)
- Kilowatt
- Horsepower
Correct answer: Ton of refrigeration
A ton of refrigeration equals 12,000 BTU/hr, and is the standard US unit for expressing refrigeration system capacity.
Question 3: The 'transmission load' in a refrigeration system refers to heat that enters through:
- Door openings during loading and unloading
- The walls, floor, ceiling, and other structural surfaces (Correct answer)
- The product being stored in the space
- Lights and fans operating inside the refrigerated area
Correct answer: The walls, floor, ceiling, and other structural surfaces
Transmission load is the heat that conducts through the building envelope (walls, ceiling, floor) due to the temperature difference between inside and outside.
Question 4: What does 'product load' represent in a refrigeration load calculation?
- The weight capacity rating of the refrigeration equipment
- Heat added by people working inside the refrigerated space
- The heat that must be removed from goods being cooled or frozen (Correct answer)
- The electrical load of the evaporator fan motors
Correct answer: The heat that must be removed from goods being cooled or frozen
Product load accounts for the heat content of the goods being stored or processed, including sensible cooling and any latent heat for freezing.
Question 5: When calculating refrigeration load, what is the 'equipment load' component?
- Heat generated by lights, fan motors, and other equipment inside the space (Correct answer)
- The rated BTU capacity of the condensing unit
- Heat load caused by the refrigerant compressor
- The weight of the refrigeration equipment installed
Correct answer: Heat generated by lights, fan motors, and other equipment inside the space
Equipment load includes heat added by evaporator fan motors, defrost heaters, lights, forklifts, and any other heat-generating equipment operating inside the refrigerated space.
Question 6: What safety factor is most commonly applied to a calculated refrigeration load when selecting equipment?
- 5–10%
- 15–20% (Correct answer)
- 25–35%
- 40–50%
Correct answer: 15–20%
A 15–20% safety factor is standard practice to account for variations in usage, product loading patterns, and unforeseen heat gains not captured in the calculation.
Question 7: Which load component must be included when a refrigerated warehouse receives large quantities of warm product throughout the day?
- Transmission load
- Equipment load
- Pull-down load (Correct answer)
- Infiltration load
Correct answer: Pull-down load
Pull-down load is the additional capacity needed to reduce incoming warm product to the design storage temperature within an acceptable time period.
RSES System Design & Load Calculation 1
What is the primary purpose of performing a refrigeration load calculation before system design?