Industrial chillers are critical equipment in manufacturing, as they are essential in minimizing the threat of production downtime or product quality contamination that may be caused by excess heat in a process or application. Specifically, industrial chillers protect a process’ integrity by removing excess heat from equipment and applications that are sensitive to high temperatures; examples include those in the food and beverage, plastics, and printing industries. By using and re-circulating a facility’s own water supply, industrial chillers also help to decrease a plant’s water consumption, lower the costs associated with cooling water, and bypass the need to have access to a municipal water supply and wastewater discharge system.
Things to Consider When Selecting an Industrial Chiller
Thinking of specifying an industrial chiller installation for your facility? There are five key items that you should consider to ensure that you select the right product: the type of process fluid that will be used; the process cooling temperature; the pressure and flow requirements; the operating environment; and the chiller size needed.
Process Cooling Fluid. When you’re choosing a cooling fluid for your process, you should consider both how a fluid performs and its equipment compatibility. The performance of a specific fluid is based on its properties at a given temperature, such as specific heat, viscosity, and its freezing and boiling points. When considering equipment compatibility, be sure to consider both the materials and fluids being used, given that the potential for corrosion and early seal degradation commonly happen in incorrectly sized systems.
Cooling Fluid Temperature. Know your chiller’s performance data! A chiller’s cooling capacity is directly affected by the setpoint temperature, meaning that a direct relationship between the temperature at which the chiller is set and its total cooling capacity. A decrease in temperature will put an increased load on the refrigeration system, while increasing the temperature will do the opposite.
Process Pressure and Flow Requirements. Did you know that a pump’s size and performance help to determine a system’s pressure loss, as well as its necessary flow rate? That’s right!
Pressure. To determine the pressure loss across a system, place pressure gauges at the process’s inlet and outlet and then apply pump pressure to obtain the values at the desired flow rate. Keep in mind that an undersized pump will reduce the fluid flow rate through the entire cooling loop. If the chiller has been equipped with internal pressure relief, the flow will be diverted around the process and back into the chiller. If there is no internal pressure relief, the pump will attempt to provide the necessary pressure and run at what is referred to as dead-head pressure, or limit. When this state occurs, the pump’s life can be drastically reduced; liquid ceases to flow and the liquid in the pump becomes hot, eventually vaporizing and disrupting the pump’s ability to cool. This results in excessive wear to bearings, seals, and impellers.
Flow. Inadequate flow through the process will yield inadequate heat transfer so the flow will not remove the heat necessary for safe operation of the process. As the fluid temperature increases beyond the setpoint, the surface/component temperatures also will continue to rise until a steady-state temperature that is greater than the initial setpoint is reached.
Operating Environment. Knowing the site conditions of where your chiller will be operating is essential to selecting the best product fit for your process! Ambient temperature and spatial constraints are especially important to consider.
Ambient Temperature. An air-cooled chiller’s ability to dissipate heat is affected by the ambient temperature, as the refrigeration system uses the ambient air/refrigerant temperature gradient to induce heat transfer for the condensation process. A rising ambient air temperature decreases the temperature differential (Δ) which reduces the total heat transfer. If the chiller uses a liquid-cooled condenser, high ambient temperatures can still have negative effects on key components such as the compressor, pump, and electronics. These components generate heat during operation, and elevated temperatures will shorten their lifetime. As a guideline, the typical maximum ambient temperature for non-exterior rated chillers is 104° fF
Spatial Constraints. To maintain the proper ambient air temperature, it is important to provide adequate air circulation space around the chiller. Without proper airflow, recirculation of an inadequate volume of air rapidly heats it up. This will impact chiller performance and potentially can damage the chiller unit.
Chiller Size. Selecting a correctly sized chiller is a crucial decision. An undersized chiller will always be a problem – never able to properly cool the process equipment and the process water temperature will not be stable. In contrast, an oversized chiller will never be able to run at its most efficient level and prove more costly to operate. To determine the correct size of unit for the application it is necessary to know the rate of flow and the heat energy that the process equipment is adding to the cooling medium, i.e., the change in temperature between the inlet and outlet water, expressed as the ∆T.