Tube-in-Tube or Double Pipe Condenser:

In this type of condenser, a smaller diameter pipe inserted inside a greater diameter pipe is bent to the required form. Water pass out through the inner tube & the refrigerant by   the annular space among the two tubes; the flow of refrigerant & water being arranged in opposite direction to obtain the greatest benefit of heat-transfer. Because of the impurities exist in water, scale may form on the water-side of the tube that can impede the heat transfer; also muck may settle on the surface. Thus it becomes essential to periodically clean the water tube. However in the tube-in-tube system, cleaning is not simple, unless a removable header is provided to attach all of the tubes.

             Schematic Representation of a Two-Pass Water-Cooled