Unit 21 Evaporators and the refrigeration system

7. A low evaporator superheat indicates.

A low evaporator superheat indicated system restriction.

6. What does a high evaporator superheat indicate.

A starved evaporator.

14.List seven avantages that an aluminum parallel flow plate fin vibrator has over a standard round copper tube plates Finn evaporator.

Advantages of Aluminum parallel flow, plate/fin evaporator are: Reduce static pressure thru the coil-which means fewer fan watts and less horsepower. - Reduces coil depth for the evaporator and condenser, which leads to easier cleaning an less air side static pressure. - Reduced internal volume reduces refrigerant charge . - Reduced face area of condenser and evaporator. - smaller footprint for the condensing unit - A 30% coil rate and size reduction - A reduction in packing costs size and weights. - corrosion resistance - lower system costs.

2. Rerigerant in the evaporator.

Changes from a liquid to vapor.

10. An evaporator that is not flooded is thought of as what type of evaporator.

Dry-type evaporators are also called direct-expansion evaporators.

12. What is commonly used to defrost the ice from low temperature evaporator.

Hot gas defrost or electrical heaters.

8. Why are multicircuit evaporators used?

Multicircuit evaporators keep excessive pressure drop from occurring in the evaporator.

3. The sensible heat that is added to a saturated vapor after all the liquid has boild away is referred to as.

Superheat.

1. What is the function of the evaporator in the refrigeration system.

The evaporator, absorbs heat into the refrigeration system.

4. What determines the pressure on the low-side of the system.

The metering device.

9. Flooded evaporators use a(n) _______ type of expansion device.

Use a float metering device to keep the liquid level as high as possible in the evaporator.

11. When an evaporator experiences a heat-load increase the suction pressure.

increases.

13. A mediume temp refrigerator box operates at which temperatures.

28F to 40F.

5. A refrigerant system's evaporator typically runs about _______ degrees of superheat .

8 to 12F of superheat.