Flooded Evaporator:

In a flooded-type evaporator a regular refrigerant liquid level is maintained. A float valve is utilized as the throttling apparatus which maintains a regular liquid level in the evaporator. Because of the heat supplied by the substance to be cooled up, the liquid refrigerant vaporizes and therefore the liquid level falls. The float valve opens up to admit more liquid and therefore maintains a continuous liquid level. As a consequence, the evaporator is always filled up with liquid to a level as find out by the float adjustment and the inside surface is wetted along liquid. Therefore this kind is called the flooded evaporator. The heat-transfer efficiency enhance because the entire surface is in contact along the liquid refrigerant and, thus, the flooded evaporator is more efficient. But the refrigerant charge is comparatively large as compared to the dry-expansion type. Since the evaporator is filled up with liquid, this is obvious that the vapour from the evaporator shall not be superheated but shall be at saturation. To stop liquid carry on to the compressor, generally accumulators' are utilized in conjunction having flooded evaporators. The accumulator also serves like the chamber for the liquid level float valve. The evaporator coil is attached to the accumulator & the liquid generally flow from the accumulator to the evaporator coil is by gravity. The vapour created by the vaporization of the liquid in the coil being lighter, arises and passes on the top of the accumulator from where it enters the suction line as indicated in given figure. In some of cases, liquid eliminators are provided in the accumulator top to stop the possible carry-over of liquid particles through the accumulator to the suction line. Furthermore, a liquid-suction heat exchanger is utilized on the suction line to superheat the suction vapour. For some of the applications, a refrigerant liquid pump is employed for circulating the liquid from the accumulator to the evaporator coil & such a system is known as a 'liquid-overfeed system'. When the terms 'flooded' & 'dry expansion' point out the manner in which the liquid refrigerant is fed into the evaporator and circulated, the terms 'natural convection' & 'forced convection' explain the way in which the fluid (air or liquid) is cooled/circulated around the evaporator.

Natural convection relies on the movement in a fluid, where the colder layer at the top being heavier falls down and the warmer layer rises up. By having an evaporator in the topmost portion of an insulated cabin, the air inside the cabin gets cooled up by natural convection. A domestic refrigerator is a distinctive instance. In 'forced-convection' types, the fluid is 'forced' on the evaporator via a fan or a liquid pump. In a room air conditioner, a fan constantly circulates the room air over the cooling coil and therefore cools the room air. In a chilled-water system, a brine pump or water pump circulates the fluid via the chiller & cooling coils. For a 'coil-in-tank' arrangement, such like in an ice plant, an agitator is utilized to move the brine over the cooling coil along a certain amount of velocity.