As one of the most important parts in a chiller, the purpose of evaporator is to transfer the cooling energy from cold refrigerant(gas) to water or other coolant. There are three main types of evaporator for industrial chillers, they are coil type, shell and tube type and plate type. Here we are comparing these three types of evaporators from aspects of Heat Transfer Efficiency, Requirement for Water Quality, Convenience of Maintenance and Space Occupation.
1. Heat Transfer Efficiency.
Heat transfer efficiency is very important for a heat exchanger. Normally, plate type evaporator has the highest efficiency than others, because its more precise structure. Shell and tube type ranks second in this list, while coil type has relevantly the poorest efficiency amongst the three types of evaporators.
Heat efficiency needs to based on heat exchange area, higher efficiency means it can transfer more energy with less heat exchange area. On the other hand, if the efficiency is lower, we need larger heat exchange are.
2. Convenience of Maintenance.
As coil type evaporator has the simplest structure, and it is normally built in a water tank with removable cover, it is most convenient for maintenance and clean.
Shell and tube type evaporator needs to open the end cover when doing maintenance, which is more complicated than coil type.
Plate type evaporator has the poorest maintainability amongst the three of them, as its disassembly is the most difficult. Some of them are not even detachable.
Below is structure drawing of plate type and shell and tube type evaporator for reference.
3. Requirement for Water Quality.
Generally speaking, plate evaporator and shell and tube evaporator requires high water quality because their lower maintainability. But plate type evaporator has even higher requirement, because its water runner is the finest and easy to be jammed by foreign substance.
On the other hand, coil type evaporator does not require the water to be very clean, because of its rough structure and high maintainability.
When it comes to corrosiveness of water, all the three types of evaporator needs to use anti-corruption material.
4. Space Occupation.
Coil type evaporator is normally built in a water tank, it immerses in water while using. If we are considering assembly space, copper coil type evaporator requires the minimum, therefore it will save most space in a chiller structure. Simply because it does not occupy any extra space besides the water tank. But still, its immersion will decrease the capacity of the reservoir tank.
Plate type evaporator has the most precise structure comparing to the other two competitors, therefore it has the smallest size actually. But since it is not built in the water tank, it will occupy some more room inside a chiller than coil type evaporator.
Shell and tube evaporator requires the most space amongst the three of them. There is water reserved in the shell of it, yet the volume is not quite enough for a cooling circuit, so we still need a water tank. On the other hand, shell and tube evaporator is normally horizontal type, which makes it less compact even.
In conclusion, as for space occupation, Coil Type<Plate Type<Shell and Tube Type.
Why do we care about space occupation for a chiller component? Because if based on same machine dimension, less space occupation means more space for maintenance. It is not a crucial point but still an aspect to consider for.
When sizing an industrial chiller, Senho will suggest the most suitable solution as per your actual conditions. But incase you need to make the choice by yourself, this might help you.