Introduction of Basic Knowledge on Refrigeration

Basic Principle of Refrigeration

Evaporation relates to heat absorption; all liquid must absorb heat when evaporates.

Condensation relates to heat release; all steam must release heat when condenses.

The refrigerant, which evaporates and condenses easily, is preferred medium of heat absorption and release. Only a little refrigerant can absorb or release much heat when evaporating or condensing. With low temperature the steam is likely to evaporate to reach the temperature we desired.

Refrigerant is converted from liquid state into gaseous state in the evaporator. Refrigerant pipes enter from the upper part and discharge from the lower which brings up the air flow.

Refrigerant is converted from gaseous state into liquid state in the condenser. Refrigerant pipes enter from the lower part and discharge from the upper which brings down the liquor.

Compressor compresses the gaseous refrigerant at low pressure and low temperature into gaseous refrigerant at high pressure and high temperature and maintains this state which is the most important in the whole system. A general power of the compressor accounts for 25%~30% of the cooling capacity of the main refrigerator.

Water pipes will expand when heated and contract when cooled, so the low-temperature pipe lies below and high-temperature pipe lies above to be in favor of water flow.

Chilled water is the circulating water that flows from the main refrigerator to the equipment to be cooled.

Cooling water is the circulating water that flows from cooling water tower to the main refrigerator.

Applications Scope

With the development of industrial modernization and automation, water chiller has played an important role in different production processes. It is applied in the field of cooling moulds in machinery molding, which can not only largely improve its surface smoothness but also reduce its surface check and internal stress. The unshrinkable and non-deformed product is convenient for stripping and molding to improve tremendously the production efficiency of the molding machinery.

Portable water chillers are also applied to cooling machine tools, which can control oil temperature precisely and reduce thermal deformation efficiently and improves machining precision. Besides, chilling water system which applies to beverage cooling and packing can make high-temperature beverage lowered to a desired value to ensure quality of it and quicken industrial flow, etc.

Introduction of Refrigerants
R22

R22 is also called Freon, whose molecular formula is CHCIF2. It is colorless gas at room temperature and can be liquefied into colorless and transparent liquid when pressurized. As the best refrigerant regarding to its comprehensive performance, R22 is the most widely-used refrigerant all around the world with mature technology. It has stable and safe chemical composition, non-inflammability and high energy efficiency. Unfortunately, it damages the ozone sphere.

The refrigerant pressure of R22 varies along with different temperature instead of other factors. The weight of the refrigerant can not be measured by the size of pressure.

R407C

R407C consists of R32 / R125 / R134a and 23 / 25 / 52wt.%. The cooling capacity of unit volume, evaporation pressure, condensation pressure, exhaustion temperature and comprehensive thermal property is similar to R22, and its heat transfer coefficient is 10% lower than that of R22. Polyol Ester Oil is the lubricant adopted by the compressor. Before new refrigerant is poured into the system, all R407C should be discharged, with reduced filling charge and extended capillary.

R410A

R410A consists of R32 / R125 and 50 / 50wt.%. The condensing pressure of it is about 60% higher than that of R22, and the cooling capacity of unit volume is 50% more than that of R22. Under the same test condition, its heat transfer coefficient of condensation is about 2~6% higher and the pressure loss is 20~40% lower than that of R22, and heat transfer coefficient of evaporation is 20~30% higher than that of R22. System that uses R410A and Polyol Ester Oil is more compact than that uses R22. All R410A should be discharged before new refrigerant is poured into the system.