Industrial Refrigeration
About Industrial Refrigeration Systems
Industrial refrigeration systems are essential to food and beverages, pharmaceuticals, chemical processing, and more. Whether at a stationary facility or in transit, cooling units keep materials and products at the right temperature to avoid degradation and spoilage, and are found in areas ranging from dairy transport to plastics manufacturing.
How Do Refrigeration Systems Work?
Refrigeration occurs by removing heat. This principle of heat transfer is the Second Law of Thermodynamics: heat always moves spontaneously from hot to cold, and continues to do so until thermal equilibrium is reached. A second principle is the Pressure Law, which states that within a constant volume, the pressure of a gas is directly proportional to its temperature. In other words, the higher the gas pressure, the hotter the gas, and vice versa.
Very basically, a refrigeration system circulates a refrigerant that changes states from low pressure/low temperature to high pressure/high temperature, and back again.
1. A compressor pressurizes the gaseous refrigerant, making it hot.
2. The hot refrigerant travels through a condenser outside the refrigeration system. When the gas encounters the cooler air temperature, the refrigerant begins to condense into a liquid.
3. This liquid goes through an expansion valve or fixed orifice. This throttling device quickly drops the refrigerant’s pressure to produce a mixture of cold liquid and vapor.
4. This cold refrigerant now flows through the evaporator tube inside the refrigeration system, removing heat as it does so.
5. The refrigerant is now back at a low pressure and lower temperature. When the system’s temperature goes above a certain threshold, the thermostat tells the compressor to start the cycle again.
Compared to home refrigeration, industrial systems are more intricate as they might need to:
- Handle high ambient temperatures
- Cool to very low temperatures
- Cool large areas/volumes
Some industrial refrigeration units use multistage cooling to attain very low temperatures, such as for vaccine storage. Many have cooling units for the condenser. WIKA has the products and expertise to be a valuable partner, regardless of how unique the application.
Refrigeration Safety Standards and Requirements
The refrigerant’s enthalpy – basically, the amount of heat it can hold – and quantity determine the refrigeration system’s cooling ability. Other characteristics, such as its corrosiveness and the pressure required to condense it, affect the choice of system components and instrumentation. Each refrigerant has an ASHRAE designation, commonly called an R number.
For years, the refrigerants of choice were hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), and chlorofluorocarbons (CFCs). Although highly effective, CFCs and HCFCs thin the ozone layer, while HFCs contribute to global warming. For these reasons, countries around the world have banned or are phasing out these compounds, and mandate refrigerants with zero or very low ozone depletion potential (ODP) and global warming potential (GWP). These natural refrigerants include:
- Air
- Water (R-718)
- Carbon dioxide (R-744)
- Hydrocarbons: propane (R-290), isobutane (R-600a), etc.
- Ammonia (R-717)
Each refrigerant has its own set of advantages, disadvantages, and operating conditions, adding another layer of complexity to the design and operation of an efficient industrial refrigeration system.
Measuring Instrumentation for Industrial Refrigeration
Measuring instruments for industrial refrigeration systems must comply with safety regulations and energy efficiency standards. In general, the type of refrigerant imposes the most safety and operating requirements. For example, CO2 needs high pressure to condense, thereby requiring heavy-duty pressure switches and transmitters. Hydrocarbons are flammable, so instrumentation has to be explosion-proof. Ammonia is toxic and highly corrosive, thus instruments need to be properly sealed (leak-free) and have corrosive-resistant materials such as stainless steel for the case and wetted parts.
WIKA has reliable, high-quality options for monitoring all aspects of industrial refrigeration systems, such as:
- Ambient temperature — one of the factors that determine heat load
- Refrigeration system temperature
- The refrigerant pressure and level in the compressor
- The refrigerant’s temperature at the condenser and evaporator
- Differential pressure at the expansion valve
We carry a wide range of mechanical and digital instruments for industrial refrigeration systems:
Temperature
Pressure
WIKA’s Expertise in Industrial Refrigeration
With decades of experience in refrigeration, WIKA has the product portfolio and industry expertise you seek. It can be difficult to select the right pressure gauge, temperature sensor, and other instruments for your applications. Contact us for help in finding the optimal measurement solutions for your industrial refrigeration applications.