How to choose a suitable evaporator type open type or closed type

How to choose a suitable evaporator type? open type or closed type? 

When you buy the water chiller machine, supplier will ask you : what type of evaportor you need? if you don't know how to choose, here is share you. 

As usual, there have 3 types evaporator, 1. Tank with coil type, 2. Shell and tube type, 3. Plate Heat exchanger type. 

Tank with coil evaporator is a open type circulation, the shell and tube, and plate heat exchanger is a closed type circulation.  

In order to ensure the pump working pressure is balance, so when user side is a closed type water loop, for example a Jacket tank, or PHE, or fermentation tank, can choose the tank with coil type. 

When user side is a open type water loop,for example glycol tank,  can choose the other two type. 

Usually, for brewing customer, if they will cooling for sereral fermentation tanks, need equipped with glycol tank, so they need to choose the closed type evaporator, PHE type use more in this field.

Now let's see what's the difference and their characteristics

1.Tank with coil type : 

● Advantage: 

The internal tank can storage some cooling capacity, will reduce the open time and energy regulation of the chiller, then the cold water temperature can fluctuate less.

● Dsadvantage 

• Cold water contact with the atmosphere, high oxygen content in circulating water, should be corroded pipeline. 

• When the height difference between the user equipment and the chiller, the water pump must overcome the hydrostatic pressure caused by the height difference and increase plus power consumption.

2. Shell and tube,  Or Plate Heat Exchanger type 

● Advantage:

• Because the pipeline is not in contact with the atmosphere, the pipeline and equipment should not be corroded.

• There is no need to provide static water pressure for high equipment, circulation pump pressure is low, so the pump power is relatively small. 

• Because there is no return tank, no gravity return water, return water does not need another pump, so the investment is less, the system is simple. 

● Disadvantage 

• Low cold storage capacity , when the load is low, the refrigerator needs to be started frequently. 

• Sometimes a pressurized water pump is needed to refill the expansion tank. 

Welcome communicate with me if you have any different idea or knowledge, I'm glad to learn and improve myself with you.