Ejector Cooling Systems
The first steam ejector cooling system was developed by Maurice Lablanc in 1910 and was widely used in applications until 1930’s. Ejector cooling systems have lost their use due to the use of chlorofluorocarbon refrigerants developed during the 1930’s in mechanical compression refrigeration cycles. In spite of these negativities, research and development studies on ejector cooling systems continue today. Ejector cooling systems; it is preferable to use ejector cooling systems in industrial plants where only refrigeration needs waste or very inexpensive energy. Because ejector cooling systems are cheaper than steam compression mechanical cooling cycles in terms of total cost. With ejector cooling systems it is possible to obtain a temperature between 0 ° C and 20 ° C if there is waste and low cost energy at 60-150 ° C. The most important disadvantage is that the efficiency coefficients (EER = 0.2-0.3) are lower than those of vapor compression mechanical and absorptive refrigeration cycles. Furthermore, as the system is removed from the design conditions during operation, the EER values decrease.
Ejector cooling system
As seen above, an ejector cooling cycle consists of two different circuits. The first circuit (1-2-3-4-1) is the power circuit and the second circuit (1-2-5-6- 1) is the cooling circuit. In the power circuit, the high-pressure fluid is vaporized by the energy (Qb) supplied from the outside in the boiler or generator (3-4). This high-pressure steam, also referred to as the first fluid, is pulverized at high speed through the ejector nozzle. With this pressure drop (vacuum), the refrigerant in the evaporator (6) is absorbed. These two fluids are mixed in the mixing cell before entering the diffuser in the ejector where the resistance builds up and the flow slows down. This mixture entering the condenser then condenses by giving heat (Qc) to the environment (1-2). A portion of the liquid at the condenser outlet (2) is sent back to the boiler by the pump and the power cycle is completed. The other remaining fluid mixture is passed through the expansion valve for cooling and the pressure is reduced. This pressurized fluid enters the evaporator in a liquid-vapor mixture (5). The evaporator evaporates by drawing heat (Qe) and the cooling process is performed (5-6).These operations are repeated continuously.
In order to obtain temperatures below 0 ° C in ejector cooling systems, work should be done to apply other fluids (such as CO2) to these systems instead of water. During food production and transportation in the food sector, where waste heat is high, chiller heat can be used in places where power and heat production are also known as tri-generetion. In recent years, some companies have been working to use the ejector cooling system in car air conditioning applications.