How heat exchangers work in chilled water systems

Heat exchangers help chilled water systems move thermal energy between separate loops without mixing fluids, supporting pressure control, fluid isolation, and equipment protection. LOUMIS Air’s Jennifer Lingo says the devices matter most when buildings need different temperatures, pressures, or fluids in one mechanical network.

Why it matters: - Heat exchangers let chilled water systems move heat while keeping separate water loops physically isolated. - That separation can help manage pressure, protect equipment, and support different operating conditions across large buildings and facilities. - The role becomes more important when systems use different fluids, different pressures, or multiple cooling zones.

What happened: - Jennifer Lingo of LOUMIS Air outlined how heat exchangers fit into chilled water systems used in commercial, institutional, and industrial buildings. - LOUMIS Air services locations in Louisiana and Mississippi. - The explanation focused on how heat exchangers transfer thermal energy without allowing the fluids to mix. - A shared Facebook link was included in the source material: Rhino Digital on Facebook.

The details: - Chilled water systems use a chiller to remove heat from water. - The cooled water moves through piping to air-handling units, fan-coil units, process equipment, or other components. - Warm return water flows back to the chiller, where heat is removed again. - Heat exchangers can appear at several points in that cycle, depending on system design. - In a plate-and-frame heat exchanger, fluids move through alternating channels separated by thin metal plates. - In a shell-and-tube heat exchanger, one fluid flows through tubes while another fluid moves around them inside an outer shell. - Both designs transfer heat through a conductive surface while keeping fluids separate. - Large buildings may use multiple chilled water loops. - A central plant can feed chilled water to several buildings or sections of a large facility. - Heat exchangers can separate primary and secondary loops that serve individual buildings, floors, or processes. - Loop separation can simplify pressure management in tall buildings, where water pressure rises at lower elevations. - Separate loops can also support different flow rates or temperature requirements in different areas. - Some systems use water mixed with glycol to reduce freezing risk in piping or equipment exposed to low temperatures. - A heat exchanger can connect a glycol loop and a water loop without spreading glycol through the entire chilled water system. - That approach can be useful for outdoor equipment, process cooling, refrigeration-related systems, and other freeze-protection applications. - Keeping fluids separate can also reduce treatment complexity when different parts of a system need different chemical conditions. - Building additions, renovations, new equipment, or changes in building use can create new cooling loads. - Heat exchangers can help connect those new loads while keeping them separate from an existing water circuit. - Engineering decisions depend on capacity, temperatures, flow rates, pressure conditions, piping layout, and the intended use of the new equipment. - Heat exchanger performance depends on clean surfaces that allow heat to pass efficiently between fluids. - Scale, sediment, biological material, corrosion products, and other deposits can reduce heat transfer. - Deposits can force the system to use different flow conditions or more equipment operation to achieve the same cooling effect. - Water treatment can therefore include monitoring water chemistry, filtration, corrosion control, and biological growth. - Heat exchangers are designed for specific flow rates and temperature conditions. - Too little flow can reduce heat transfer. - Too much flow can increase pressure drop, pumping requirements, erosion, or other operating concerns. - Control valves, pumps, sensors, and building automation systems can regulate flow as cooling demand changes. - Temperature readings before and after the exchanger can help identify load changes, restricted flow, fouling, or control problems. - Heat exchangers can also isolate older piping, different treatment requirements, high-pressure sections, or process fluids from sensitive equipment. - That thermal connection without direct fluid connection is useful in large facilities with multiple mechanical systems. - Hospitals, hotels, office buildings, universities, manufacturing facilities, and data centers may all use chilled water networks with different operating needs. - Heat exchanger selection depends on cooling load, water temperatures, allowable pressure drop, fluid type, available space, maintenance access, operating pressure, and other engineering factors. - Plate-and-frame units may fit compact applications with strong heat-transfer needs. - Shell-and-tube units may fit different operating conditions. - Pumps, valves, controls, strainers, piping, and sensors also affect how the exchanger performs within the full system. - LOUMIS Air’s Jennifer Lingo said heat exchangers should be viewed as part of the entire chilled water system, not as isolated equipment.

Between the lines: - The article frames heat exchangers as a design tool, not just a component. - Their value comes from solving system-level problems such as pressure differences, fluid compatibility, and retrofit complexity. - The emphasis on fouling, flow, and water treatment suggests maintenance can matter as much as initial equipment choice.

What's next: - Building operators considering expansions, equipment changes, or retrofits may need to recheck flow, temperature, and pressure requirements before adding a heat exchanger. - Systems with freezing risk, mixed fluids, or multiple building zones may be the most likely candidates for this approach. - Ongoing monitoring of water quality, flow conditions, and temperature differentials will remain important for performance.

The bottom line: - Heat exchangers keep chilled water systems flexible by moving heat across separate circuits without mixing the fluids.