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Introduction to Types and Characteristics of Condensers

Date:Mar 18, 2020

Condensers can be divided into water-cooled, air-cooled and evaporative types according to their cooling media.


I. Water-cooled Condenser

The water-cooled condenser uses water as the cooling medium, and the heat of condensation is taken away by the temperature rise of water.  Cooling water is generally recycled, but cooling towers or cooling pools are required in the system.  Water-cooled condensers can be divided into shell-and-tube condensers and double-tube condensers according to their structural forms. Shell-and-tube condensers are common.


1. The main features of vertical shell-and-tube condenser are:


1.1. Due to large cooling flow rate and high flow rate, the heat transfer coefficient is relatively high, generally K = 600 ~ 700 (kcal/m2 h℃).


1.2. The vertical installation covers a small area and can be installed outdoors.


1.3. The cooling water flows straight through and has a large flow rate, so the water quality is not high, and the general water source can be used as cooling water.


1.4. The scale in the pipe is easy to remove and it is not necessary to stop the refrigeration system.


1.5. However, due to the fact that the cooling water temperature in the vertical condenser is generally only 2 ~ 4℃, the logarithmic mean temperature difference is generally 5 ~ 6℃ on the left and right, so the water consumption is relatively large.  And because the equipment is placed in the air, the pipe is easy to be corroded, and the leakage is easy to be found.


2. Horizontal shell-and-tube condenser: It has a similar shell structure to that of vertical condenser. The main difference lies in the horizontal placement of the shell and the multi-channel flow of water.  The cooling pipe of Freon horizontal condenser generally adopts low-rib copper pipe.  This is due to the low heat release coefficient of Freon.  It is worth noting that some Freon refrigeration units generally do not have liquid storage tanks, but only use a few fewer rows of tubes at the bottom of the condenser to serve as liquid storage tanks.


3. Bushing condenser: refrigerant vapor enters the cavity between the inner and outer tubes from above and condenses on the outer surface of the inner tube. Liquid flows down the bottom of the outer tube in sequence and flows into the liquid reservoir from the lower end.  Cooling water enters from the lower part of the condenser and flows out from the upper part through each row of inner pipes in turn, in countercurrent with the refrigerant.  The condenser has the advantages of simple structure and convenient manufacture, and has good heat transfer effect due to single-tube condensation and reverse flow direction of medium. When the water flow rate is 1 ~ 2m/s, the heat transfer coefficient can reach 800 kcal/(m2 h℃).  The disadvantage is that the metal consumption is large, and when the number of longitudinal tubes is large, the lower tubes are filled with more liquid, which makes the heat transfer area not fully utilized.  In addition, the compactness is poor, cleaning is difficult, and a large number of elbow joints are required.


II. Air-cooled Condenser

Air-cooled condenser uses air as cooling medium and takes away the heat of condensation by the temperature rise of air.  This kind of condenser is suitable for occasions with extreme water shortage or no water supply, and is commonly used in small freon refrigeration units.  According to different air flow modes, it can be divided into natural convection and forced convection.


The heat exchange of evaporative condenser mainly depends on the evaporation of cooling water in the air to absorb latent heat of vaporization.  According to the air flow mode, it can be divided into suction type and pressure type, as shown in the figure.  Evaporative condenser consists of cooling tube group, water supply equipment, ventilator, water baffle and box body.  The cooling tube set is a serpentine coil set made of seamless steel tubes bent and installed in a rectangular box made of thin steel plates.  Ventilators are arranged at the two sides or the top of the box body, and the bottom of the box body also serves as a cooling water circulating pool.  It is a parallel device based on evaporative condenser and shell-and-tube condenser.


Three, air cooling condenser

Air-cooled condenser uses air as cooling medium and takes away the heat of condensation by the temperature rise of air.  This kind of condenser is suitable for occasions with extreme water shortage or no water supply, and is commonly used in small freon refrigeration units.  According to different air flow modes, it can be divided into natural convection and forced convection.


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