Liquid Chiller Notes

Things you need to know to start sizing a liquid chiller:

Temperatures: The ambient temperature is the air temperature around the liquid chiller. The desired temperature is the fluid temperature at the outlet or at a location on the item being cooled. The difference between the two is the design temperature differential (delta T). Typically the fluid temperature has to be a little cooler than the item being cooled. Make sure to include any gradients from the fluid to the test item. Also include any increase or decrease in the fluid due to the hoses. While these differences are typically small, large hose lengths and poor thermal coupling between the fluid and the device under test can increase them.

Heat Loads Active and Ambient: We define an active load as any source of heat. Waste electric heat or exothermic reactions are examples. Loads can also be related to the specific heat of a sample when cycle times are important. Ambient loads are caused by the temperature differential between the ambient and the fluid in the hoses
and the device under test. Un-insulated hoses and test items will have higher ambient loads than insulated ones. These values are often difficult to estimate but quickly measured.

Performance Curves: The total load and temperature differential (delta T) can be applied to the performance curves of the liquid chillers to determine if the capacity is sufficient. Complete details on this process can be found on Page 10.

Fluid flow requirements:
What flow rate is required? What is the pressure drop at that flow rate? Will the hoses significantly affect the pressure drop? Graphs of the flow vs. pressure drop are available for each liquid chiller.

Things you should consider when selecting a liquid chiller:

Purpose: What is the real need for cooling: maintaining electronics temperatures, precision temperature control, maintaining sample temperatures, cooling a process, temperature cycling? Is this a laboratory or industrial setting? Do I need portability? Is this an OEM application where the chiller must be packaged into your product? Answering these questions will help in selecting the correct liquid chiller for your application.

Temperature Control: Some applications simply require cooling with no fancy temperature controls. The TLC-1200 and the TLC Cubed products often best fit these needs. When better control and more control features are needed the TLC-700 and TLC-900 are used. The TLC-900 has a remote sensor feature standard allowing you to control the temperature at a point downstream or on the device under test. Each application should be evaluated independently to assure safe and proper control.

Type of Fluid: TECA recommends using distilled water. Regular tap water can be used also although “hard” water may cause mineral deposits to build up. For those applications which may go below 0 C a mixture of 25% ethylene Glycol and distilled water is recommended. Algaecides are also commonly used additives. Fluids other than water must be evaluated on a case by case basis.

Cooling Medium: All standard TECA liquid chillers are air cooled products.

Environment: In general our standard liquid chillers can handle factory, lab and office environments. No standard unit is made for outdoor or wash-down environments. Typical locations are bench top, under bench and rack mount. Custom versions have been made for many environments.

Power Input: Liquid chillers requiring universal input 100-240 VAC, 120 VAC, 240 VAC, 120/240 VAC and 24 VDC are available.

Most liquid chillers have connectors, hoses, clamps and hose insulation included as part of their standard package. What sort of connection is required at the device under test? NPT tap? Hose barb? What sizes? It’s best to answer these questions up front to avoid problems down the road.

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