Any provider of refrigeration equipment services understands that air conditioning equipment doesn&#;t actually produce cool air. Instead, it removes heat from the area it &#;cools&#;. This is how refrigeration works.
Here are the different types of refrigeration systems:
Evaporative cooling units are also referred to as swamp coolers. They work by blowing warm outdoor air over pads that are soaked in water. The water&#;s job is to absorb the heat from the air. The water then evaporates and cooler air enters your home while warm air stays out.
An evaporative cooling unit is capable of reducing the temperature in a home by about 15-40 degrees. If you&#;re in the southwestern U.S. where the climate is dry, evaporative coolers are for you. An evaporative cooling unit is easier to install and doesn&#;t cost half as much as a central air conditioner.
Mechanical compression is used in commercial and industrial refrigeration, as well as air conditioning. Most HVAC companies install this type of cooling system.
By mechanically compressing refrigerant into a cold liquid with low pressure and expanding it into hot gas with high pressure, this type of system transfers heat. Refrigerants work when pressure is applied or removed. When they absorb heat, they boil and turn into gas, then turn back into liquid form when they release that heat. The refrigerant in a mechanical-compression system boils at 40 degrees, sucking the heat out of warm indoor air.
The process in absorption refrigeration is similar to how heat is transferred in mechanical compression. However, instead of using a mechanical compressor, absorption systems use refrigerants that attract and absorb other substances. In some systems, for example, ammonia acts as the refrigerant and water acts as the absorbent. Instead of relying on electric power, heat can come from water, natural gas, steam or other fuel sources.
These systems don&#;t need water or any type of refrigerant. They rely on a thermocouple and electric current. One end of the thermocouple is hot and the other end is cool when current is directed to it. The cold side of the thermocouple is placed in the area that needs cooled so it can attract heat and remove it from the air. Thermoelectric refrigeration isn&#;t usually used for large cooling loads, but it&#;s perfect for hard-to-access small cooling loads. A good example would be electronic systems.
If you have cooling and refrigeration needs, don&#;t hesitate to get in touch with Cafco Services. We install cooling systems and also offer HVAC filter products. Call us today at (513) 242- or use our contact form.
Mar 04,
The Five Different Types of Transport Refrigeration Systems
At present, there are five types of refrigeration systems widely used in road transport refrigeration, which includes
Guchen Thermo
The five types of refrigeration systems have many differences. To help you better understand every system,has broken down each one in some summaries below.
Chilled-water refrigeration
At atmospheric pressure, the melting point of ice is 0&#;. If the temperature below 0 degree Celsius is required, then the mixture of ice and salt is used. Salt lowers the melting point of water, which means that the more salt being added in the ice water within a certain range, the lower the melting point would be. It was proved that when you add salt whose quality equals to 29% of that of the ice water to the ice water, the melting temperature of the ice will be lowered down to the lowest value of -21.2&#;.
In refrigerated transport, ice water with different salt content is selected in accordance with the required temperature of the refrigerated goods. For example, using salt ice water with a salt content of 22%, the temperature in the compartment can be maintained at -18&#; to -13&#;.
Benefits: Chilled-water refrigeration system has low investment and low operating cost.
Drawbacks: Ice water is with relatively smaller latent heat absorption compared with the rest, therefore chilled-water refrigeration system has limited effect on the cooling of vehicle compartment. In addition, the mixture of salt and ice will pollute the environment/refrigerated food, corrode the carriage and damp the cargo.
Conclusion: chilled-water refrigeration system is mainly used for refrigerated transportation of fish and other aquatic products.
Dry Ice Refrigeration
Benefits: Dry ice refrigeration system is with low operating cost, simple design, and convenient to use. The low temperature and direct sublimation to a gas makes dry ice an effective refrigeration system.
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When compared with chilled-water refrigeration, it can not only obtain a lower temperature, but also a larger cooling capacity. Therefore, the dry ice refrigeration method is suitable for frozen food transportation.
Drawbacks: The CO2 gas produced by the sublimation of dry ice can inhibit the reproduction of microorganisms, slow down the oxidation of fat and weaken the respiration of fruits and vegetables.
However, dry ice sublimation can easily cause frosting; too much CO2 gas will cause breathing difficulties and necrosis of refrigerated goods such as fruits and vegetables;
Besides, the temperature in the compartment is difficult to adjust; the cost of dry ice is high and the consumption is large, so it is less practical.
Cold Plate Refrigeration
Before transporting the goods, cold plates are pre-chilled, to make the refrigerant freeze. During refrigerated products transportation, the chilled refrigerant in the cold plates melt and absorb heat from the environment, thus keeping commodities at proper temperatures.
Structurally, cold plate refrigeration system is divided into integral type and split type.
In integral system, the power unit, cold plates and refrigeration unit are all placed on the refrigerated vehicle.
In split system, there is only refrigeration unit and cold plates. When parking, the power system drives the refrigeration unit to freeze the cold plates.
The commonly-used refrigerant is salt brine/eutectic solution whose melting point is usually about 10&#; lower than the temperature in the compartment. The components of the eutectic solution should be changed according to the desired temperature of transported goods.
Disadvantage: The cold plate device itself is heavy and large in size, occupying a certain volume of the carriage. And the traditional cold plate systems hold the body&#;s temperature during daily delivery runs of 8-15 hours.
Conclusion: cold plate refrigeration method is best suitable for short- to medium-distance refrigerated transportation in light or medium trucks.
Liquid Nitrogen Refrigeration
The system is to use liquid nitrogen vaporization to absorb heat from the compartment, to cryogenically chill food. Under atmospheric pressure, the boiling point of liquid nitrogen is -196&#;, and the latent heat of vaporization is 200kj/kg. The specific heat of nitrogen is 1.05J/g K. When every kilogram of liquid nitrogen is vaporized and heated to -20&#;, the absorbed heat is about 358kj. Liquid nitrogen has a low boiling point and is a by-product of oxygen production, so it has been widely used.
The liquid nitrogen refrigeration device has a simple structure, reliable operation, no noise and pollution; liquid nitrogen has a large refrigeration capacity, rapid refrigeration, and is suitable for quick freezing. Liquid nitrogen vaporization will not make the compartment damp, and nitrogen is good for keeping food fresh. In addition, liquid nitrogen refrigeration has precise temperature control (+/-2&#;). However, the cost of liquid nitrogen is high, and it needs to be charged frequently, so its promotion is subject to certain restrictions.
Mechanical Compression Refrigeration System
road transport refrigeration systems
Due to factors such as transport distance & time, supporting facility and running cost, mechanical refrigeration is the most widely used refrigeration cycle method among all the 5 different types of
The main reason for the widespread use of mechanical refrigeration equipment is that the refrigeration unit can provide great refrigeration performance and with heating option, which significantly extends the application scope.
truck reefer units
Compartment temperatures can be automatically and accurately adjusted. Takingfor example, its temperature range is +30&#; to -30&#; which can be used for various refrigerated goods transportation.
cold chain industry
Although mechanical refrigeration systems are with relatively complicated structures and high purchase/operation costs, it is still the most reliable and effective refrigeration method used in worldwide
If you want to learn more, please visit our website industrial refrigeration equipment.