TABLE OF CONTENTS The following table shows the three most used refrigeration systems and approximate temperature ranges.
| Approx. Temp. Range, F | Refrigerant | ||
|---|---|---|---|
| 1. | Steam Jet | 35 to 70 | Water |
| 2. | Absorption Water Lithium Bromide | 40 to 70 | Lithium Bromide solution |
| Ammonia | -40 to +30 | Ammonia | |
| 3. | Mechanical Compression (Reciprocating or centrifugal) | -200 to +40 | Ammonia, halogenated hydrocarbons, propane, ethylene, and others |
| The most common light hydrocarbon refrigerant cooling temperature ranges are: | |||
| Methane | -200 to -300 F | ||
| Ethane and ethylene | -75 to-175 F | ||
| Propane and propylene | +40 to -50 F |
Ludwig, E. E., Applied Process Design for Chemical and Petrochemical Plants, Vol. 3, 2nd Ed., Gulf Publishing Co., p. 201.
This quick but accurate graph shows the design engineer how much horsepower is required for mechanical refrigeration systems, using the most practical refrigerant for the desired temperature range.
Example. A water-cooled unit with an evaporator temperature of -40 F will require 3 horsepower/ton of refrigeration. A ton of refrigeration is equal to 12,000 BTU/hr.
Here are equations for these curves in the form:
where
y = horsepower/ton refrigeration
x = evaporator temperature, F
| Condenser temperature | |||||
|---|---|---|---|---|---|
| F | A | B | C | D | E |
| 105 | 1.751 | -2.686e-2 | 1.152e-4 | 3.460e-8 | 1.320e-9 |
| 120 | 2.218 | -2.882e-2 |
