Types of Water Cooled Condenser - Tube in Tube, Shell and Coil, Shell and Tube - Construction and Working
According to the construction water cooled condenser are classified in to
1. Tube in tube condenser
2. Shell and coil condenser
3. Shell and tube condenser
Tube in tube/ double tube condenser - construction and working
Figure shows a tube in tube condenser. It consists an arrangement of water tube inside a large refrigerant (condensate) tube. In this arrangement vapour refrigerant enters the tube at top, while the water may flow in either direction. If the water flows in the same direction of refrigerant then it is called parallel flow system, when the water flow is opposite to the refrigerant then called counterflow system. In counter flow the temperature difference between refrigerant and water is remains fairly constant throughout the condenser and it gives high heat transfer rate. In parallel flow system the temperature difference will be maximum at the inlet side and will be minimum at outlet side. I.e. the heat transfer rate decrease as it passes through the condenser.
The warm refrigerant flows over water tubes and reject the heat to water and gets cooled. The condensed liquid refrigerant then leaves the condenser at bottom. In this arrangement the refrigerant tube also exposed to the air, and some quantity of heat will be rejected to ambient air.
Shell and coil condenser - construction and working
This type consists a one or more coils enclosed in a shell. The coil may be finned or not. This can be arranged in vertical as well as horizontal. The coil inside the shell is allowed to expanding contracting with temperature rise and fall. This spring action coil helps it to withstand temperature strain. In above figure the hot refrigerant enters into shell at top. The warm refrigerate then surrounds the water coil, and water absorbs heat. The condensed refrigerant then drop to bottom of shell. Because coils are completely enclosed by the welded steel shell, the mechanical cleaning of such coil is impossible. In case of heat exchanger fouling the coils, the chemical cleaning is adopted.
Shell and tube condenser - construction and working
Shell and tube is the most common type of condenser in large chemical processing plants. In this type of condenser number of straight water tubes are enclosed a large cylindrical shell. The shell may be with or without fins. The common materials for shell are steel and copper. In ammonia refrigerating system steel tube is used because ammonia corrodes the copper. Grooved tube sheet is welded at both ends of the cylinder. The water tubes are extended to the groove of tube sheet to achieve vapour tight fit. Intermediate support are provided to avoid bending of water tube. Removable water boxes are bolted to the tube sheet. This arrangement facilitates cleaning of condenser in case of fouling.
The hot refrigerant enters the shell at top. Refrigerant reject heat to the water when it contacts with water tubes. Finally, the condensed refrigerant drops to the bottom of shell.