Benefits of liquid-to-liquid heat exchangers include options to customize the exchangers to meet specific process specifications. Options include:
Pumps. Pumps designs that can be included in these systems range from positive-displacement to turbine to centrifugal. The pumps can be matched to the process flow and pressure requirements to ensure the best cooling performance. Choosing the correct pump for the systems can be affected not only by flow rate and pressure, but also operating temperature, specific gravity, vapor pressure and viscosity.
Coolant Fluids. The standard process fluid for temperature control systems is a mixture of water and an inhibited-glycol-based fluid. If using this standard mixture, ethylene glycol (preferred due to its lower viscosity and advanced heat transfer properties) or propylene glycol-based fluids can be chosen.
Today, more than ever, testing labs and end users are using special fluids in their processes. The liquid-to-liquid heat exchangers can be designed with wetted parts that are compatible with these special fluids. When deionized water is used, all stainless steel wetted parts should be used in the system, which includes the process side of the heat exchanger, the recirculating pump and the fittings.
PAO is becoming a more popular cooling fluid, particularly in the defense industry. When special fluids are required, the system must be designed and manufactured with compatible wetted parts. If the manufacturer knows up front the process fluid you will be using, the plate heat exchanger can be properly sized so that the system will provide the full cooling capacity.
Customizing Your Temperature Control System
November 1, 2009