Shell-and-Tube Condenser:

Given fig shows a typical shell-and-tube condenser. It is similar in construction to the flooded chiller. Several straight tubes along integral fins are stacked inside a cylindrical shell, the tube ends expanded into tube sheets that are welded to the shell at both of the ends. Intermediate tube supports are provided in the shell to ignore sagging & rattling of the tubes. AS it is very simple to clean the water-side and also, it may be easily repaired, this kind of water-cooled condenser is very popular. As ammonia affects copper, steel tubes are utilized for ammonia condensers. Water flows through the condenser water tubes when the refrigerant remains in the shell.

As copper contains a high thermal expansion & contraction rate, the tube tends to shift back and forth in the tube sheets because of the variations in temperature.

To stop the tubes from getting loose at the rolled ends because of this action, the holes in the tube sheets contain small grooves. They are just a few hundredths of mm deep. While the tube ends are rolled up or expanded in the tube-sheet holes, the copper tubes also spread out into the grooves, so effectively anchoring the tube ends to the tube sheets & preventing movement of the tubes at the ending. The expansion forces, however, can cause the tubes to bow.

Detachable water boxes are provided at the ending point of the condenser to facilitate brushing of the water tubes.

Warm (superheated) refrigerant gas enters at the top of the shell & gets cooled (desuperheated) & condensed since it comes in contact along the water tubes. The dense liquid drains off to the bottom of the shell. In some of condensers additional rows of water tubes are provided on the lower end of the condenser for sub-cooling the liquid below the condensing temperature.

Frequently the bottom part of the condenser also serves like the receiver, so eliminating the requirement of a separate receiver. but, if the maximum storage capacity (for the refrigerant) of the condenser is less than the net charge of the system, a receiver of sufficient capacity ought to be added in case the pump down facility is to be provided-such like in ice-plants, cold-storage task, etc.

Care must be taken not to overcharge the system along the refrigerant. It is because an extreme accumulation of liquid in the condenser tends to cover up too much of the water tubes and lessens the heat-transfer surface available for condensing the high-pressure gas. It result in increasing the condensing temperature and head pressure, and excessive overcharge can produce hydraulic pressures.

A safety pressure or fusible plug relief valve is fixed up on the shell of the condenser to defend the high side of the refrigeration system against excessive pressures.