Handbook of air conditioning and refrigeration / Shan K

10.22 CHAPTER TEN
Types of Condenser
Here the power input to the compressor Pcom � m˙ r Win, and Win represents the work input. Therefore,
Frej depends mainly on the difference between the condensing and evaporating pressures,
hence Frej is always greater than 1.
A condenser is a major system component of a refrigeration system. It is also an indirect-contact
heat exchanger in which the total heat rejected from the refrigerant is removed by a cooling
medium, usually air or water. As a result, the gaseous refrigerant is cooled and condensed to liquid
at the condensing pressure. Liquid refrigerant is often subcooled to a temperature up to 15°F
(8.3°C) below the saturated temperature at condensing pressure to conserve energy.
Based on the cooling medium used, condensers used in refrigeration systems can be classified
into the following three categories:
1. Water-cooled condensers
2. Air-cooled condensers
3. Evaporative condensers
10.6 WATER-COOLED CONDENSERS
Types of Water-Cooled Condenser
In a water-cooled condenser, condenser water or cooling water is used to remove condensing heat
from the refrigerant. The condenser water is often the recirculating water from the cooling tower. It
also could be from a lake, river, or well near the refrigeration plant. Groundwater discharged from
the condenser may be treated and used for other purposes. If river or lake water is used as the condenser
water, an effective water filter system, or sometimes a heat exchanger, may be necessary to
prevent fouling of condenser tubes. Use of river, lake, or groundwater is a once-through method, as
it cannot be recirculated and used as condenser water again.
If a refrigeration plant is near the seashore, sometimes seawater can be used as condenser water
if it is more economical than water from the cooling tower. Seawater is corrosive to many metals.
Copper-nickel alloy, stainless steel, and titanium are often used for water tubes in seawater
condensers. An effective filter system is necessary to prevent dirt and impurities from blocking the
water passages. Water treatment is often required to prevent the growth of living organisms. The
whole seawater intake system may be very expensive. The use of seawater is also a once-through
method.
Two types of water-cooled condensers are widely used for air conditioning and refrigeration
purposes: shell-and-tube and double-tube condensers. A double-tube condenser consists of two
tubes, one inside the other, as shown in Fig. 10.9. Water is pumped through the inner tube while
refrigerant flows in the space between the inner and outer tubes in a counterflow arrangement.
Because double-tube condensers provide limited condensing area, they are only used in small
refrigeration systems such as indoor packaged units.
Shell-and-Tube Condensers
There are two types of shell-and-tube condensers: horizontal and vertical. Vertical shell-and-tube condensers
usually incorporate a one-pass water flow arrangement. They consume more condenser water
than the horizontal type and are often located outdoors because of their height. Vertical shell-and-tube
condensers are sometimes used for ammonia refrigeration systems in industrial applications.