An industrial chiller is an equipment used to dehumidify air or cool a process fluid in industrial and commercial facilities. It can be centralized – a single chiller serving multiple applications or machines – or decentralized – each machine or application having its own chiller.
Selection Criteria for Industrial Chillers
There are four top criteria used to select an industrial chiller. These are:
- Heat load
This is the heat energy that needs to be removed to maintain or lower the application temperature. It is usually expressed in watts or BTUs.
The value of the heat load is normally provided by the equipment manufacturer. If not, you will need to identify the source of the heat energy and calculate the heat value. Heat load is comprised of different types of energy including mechanical energy (friction), electrical energy, internal energy, chemical energy and pump heat generated by the chiller.
There are two ways to determine the heat load of an industrial chiller:
Method 1: Standard heat load calculation
This method is used to calculate the heat load of an application currently running on Process Cooled Water (PCW) or tap water. It can be calculated by measuring the outlet temperature, inlet temperature, and flow rate.
BTU = GPHx8.33lbs/gallonx
For metric units of measure
Kcal = LPHxΔT(°C)
Kcal x 1.16watts/Kcal = watts
Method 2: Kilo-Volt-Amps (Kva) calculation
This method is used to calculate the heat load of an application that is new or not in running condition. It can also be used if the measurements in Method 1 are not available. The total power consumption can be calculated using the following formula:
Kva = Amp x Voltage x √phase
- Desired coolant temperature
The heat load and desired coolant temperature are used together to determine the compressor size of an industrial chiller. The lower the desired temperature and/or the higher the heat load, the larger the compressor needs to be to function optimally.
- Flow rate
This is the volume of fluid passing through a given surface per unit time. To determine the flow rate:
- Use the manufacturer’s specifications.
- If the flow rate is not provided by the manufacturer, choose the largest flow pump available.
- Pressure loss
Pressure loss is the difference in pressure between two points in a flow system. The reduction in pressure is caused by friction within the fluid itself and between the fluid and the walls of the enclosed surface. The faster the fluid, the greater the pressure loss.
The flow rate and pressure loss are used to determine the size of pump needed to meet the flow rate requirement.
Other factors to keep in mind when choosing an industrial chiller include:
- Site-specific considerations such as ambient temperature, site heat, relative humidity, altitude and air cleanliness
- Special application requirements including re-circulation system, refrigeration system, and control system among others.
- Preventive maintenance – this aspect is often overlooked when choosing industrial chillers. Be sure to choose a chiller that requires a small amount of fluid to operate. Additionally, it should have a filter that can be cleaned and reused.