Selecting The Cooling Method
Once the coolant is selected, the next step is to select the cooling method. This refers to whether refrigeration is employed or not, and how the heat (which the primary recirculating coolant removed from the heat load) is finally dissipated. Our most popular RU-300, with water as the primary coolant, utilizes refrigeration to remove heat from the water and reduce its temperature below ambient. This heat is then exhausted via the refrigeration condenser to ambient air. This is a refrigerated, air cooled unit. But this heat (a combination of the heat removed from the heat load and motor inefficiencies in the cooling unit) could raise the ambient room temperature beyond acceptable limits, causing the cooling unit to lose efficiency and possibly overload the room's air conditioning system. In such a case alternative types of cooling are available; for example, the cooling unit could be relocated outdoors (be sure to specify an outdoor unit), or the unit could be fitted with a water cooled condenser (if tap or facility water is available) to remove the heat. Another method is to employ a split refrigeration system. This allows the pumping unit to be located indoors and the condensing unit outdoors. Therefore the heat is rejected to the outdoor ambient. It should be noted that all cooling units should be located away from walls and other obstacles to provide for proper air flow.
Remember: The recirculated closed loop coolant is referred to as the primary coolant. The ultimate coolant to which the heat is finally exhausted is referred to as the secondary coolant. All performance measurements of cooling units are measured at the discharge port.
General Types of Cooling Methods - Advantages/Disadvantages
The general types of cooling methods are shown in the chart below. Other cooling methods such as ram air, liquid nitrogen cooling or other special cooling methods are also available.
Type | Model Series | Advantages | Disadvantages |
---|---|---|---|
Liquid-to-Air,
Non-refrigerated |
CU |
Highly efficient
Economical Simplest design |
Dissipates heat into room
Primary recirculated coolant is always above ambient air temp |
Liquid-to-Liquid*
Non-refrigerated |
CUW |
Quiet operation
Simplest design Most Efficient Cooling tap water is drawn only as needed |
Primary recirculated coolant is always above secondary water temp
Availability of tap/facility water Cost of tap/facility water |
Liquid-to-Air,
Refrigerated |
RU |
Best temp. control
Primary liquid is brought below ambient air temp. |
Dissipates heat into room
More expensive than CU/CUW type |
Liquid-to-Air,
Refrigerated Split System |
RU
split |
All advantages of one piece RU series
Heat is expelled outdoors Quiet operation |
Set-up cost
Typically more expensive than one piece RU series |
Liquid-to-Liquid*,
Refrigerated |
RUW |
Best temp. control
Quiet operation Primary liquid is brought below secondary (tap) water temp Cooling tap water is drawn only as needed |
Availability of tap/facility water
Cost of tap/facility water More expensive than CU/CUW series |
Air Circulating/
Cooling Unit Refrigerated & Non-refrigerated |
RC |
Circulates /cools air as primary medium
Can be refrigerated or direct heat exchange Suitable for rack or cabinet cooling |
Custom built series only-consult factory for details |
* Tap, facility water, or other liquid, provided by customer