cooler/freezer load EXAM
08/25/2010 13:16
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REFLOADS
True/False
Indicate whether the sentence or statement is true or false.


1. 
When doing a job survey for a load calculation for a cooler or freezer you should know the design ambient temperature, storage and humidity requirements, dimensions, insulation, type of construction, exposure, infiltration, product specifics, miscellaneous loads and operations. True or False?


2. 
Whenever a product load having a higher temperature that the storage placement area, the product will give its heat up until it reaches the storage temperature. Heat travels from HOT to COLD!. Is this comment True or False?


3. 
Typically when doing load calculations on a cooler or freezer a safety factor of 40% is applied to the total refrigeration load calculated? True or False


4. 
Product loads have specific heat, the amount of heat that must be removed from one pound of a product to reduce the temperature of this one pound by 1 deg F. It has two values, one above freezing and after the product has reached its freezing point. True or False?


5. 
An air change load would not consider the amount of heat entering with the airstream into a freezer or cooler assembly. True or False


Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.


6. 
To maintain the desirable relative humidity in a general purpose cooler the general purpose cooler involving meats, vegetables, and dairy products, it is common procedure to balance the low side to the condensing unit @ a _____ temperature difference? This means the temperature difference between the cooler air temperature and the refrigerant temperature in the evaporator should be?


7. 
Transmission load is the amount of heat flow through wall, floors, and ceilings. The heat gain is directly proportional to the temperature difference (TD) between the two sides of a wall. The type and thickness of insulation used in wall construction, the outside area of the wall, and the TD between the two sides of the wall are three factors that determine?


8. 
“K” factor is the insulating value of any material rated by its thermal conductivity. “U” factor is the overall coefficient of heat transfer, BTU per hour/per square foot/per deg F. “X” is equal to the material thickness in inches. The following has been established;
K = UX = X/R
U = K/X =1/R
R = 1/U = X/K
Note: K= [ thermal conductivity, BTU per (hour) (square foot) (F per inch of thickness)]
If the material is cork or mineral wool rated at K =.30 and the thickness of the material is 10” what is the R value of the material?


9. 
“K” factor is the insulating value of any material rated by its thermal conductivity. “U” factor is the overall coefficient of heat transfer, BTU per hour/per square foot/per deg F. “X” is equal to the material thickness in inches. The following has been established;
K = UX = X/R
U = K/X =1/R
R = 1/U = X/K
Note: K= [ thermal conductivity, BTU per (hour) (square foot) (F per inch of thickness)]
If the material is cork or mineral wool rated at K =.30 and the thickness of the material is 10” what is the U value of the material?


10. 
Respiration for fresh fruits and vegetable is caused because they are alive. Even in refrigeration storage they generate heat which is called the heat of _________?
The temperature of the product depends on the respiration rate.


11. 
The amount of heat that must be removed from one pound of a product to freeze this pound of product is called?


12. 
The dimensions of a cooler are width 8’, length 28’ with height of 8’. What is the volume of the cooler?


13. 
The product load of 2,000 pounds has a specific heat of 0.92 and a temperature drop of 50F. What is the product load in BTU’s?


14. 
Typically you would find 1 watt per square foot in a cooler. If the cooler had a width of 8’ and a length of 28’what would be the watts be?


15. 
If a cooler has a ceiling L of 28’ and Width of 8’ and a heat load of 72 BTU per 24 hours per one square foot of surface, what would be the total heat gain through the ceiling?



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