In the cold dryer, the condenser ACTS as a liquid refrigerant to cool the high-pressure and superheated refrigerant steam from the refrigerant compressor, so that the cooling process can be carried on continuously. The heat of the condenser is larger than the evaporator because the heat from the condenser consists of the heat absorbed by the refrigerant from the evaporator and the heat transferred from the compression work.
The condenser has air cooled (air-cooled condenser) and water-cooled (water-cooled condenser).
The characteristics of air-cooled condenser: air cooled condenser does not need cooling water, suitable for water supply difficult area or mobile application. But its heat transfer effect is worse than that of water. In high temperature or poor ventilation environment, condensation pressure is not easy to come down. Use in multi-dust environment (such as cement plant, flour mill, textile factory, etc.). The surface of the condenser is easy to accumulate dust, which affects heat transfer. Therefore, it is usually only suitable for small and medium cold dry machines.
Water cooled condenser of cooling water and water quality requirements: water cooling effect of heat transfer in the type of person who is better than air-cooled type, but its water consumption is larger, and the water quality has the following requirements: (1) into the cold of the machine (water temperature should be under 31 ℃, water temperature not more than 36 ℃; The water pressure should be kept at 0. Above 15MPa to ensure smooth flow of water (but not too high, see the machine nameplate rule); Magnesium and calcium ions in the water should not be higher than the general standard of neutral soft water; There should be no visible solid debris in the water.
Water cooled condenser cooling water piping of attention: water-cooled type person who often with other water cooling equipment (such as air compressor) together in one room, when the cooling water piping, person should be independent of the drainage outlet. If it is Shared with other water cooling equipment, it may cause backwater due to different water pressure. If it is necessary to share the drain pipe, it should be used to avoid t-word connection or reverse Angle connection.
Working principle of horizontal condenser water, high temperature and high pressure of the refrigerant vapor from the upper into the condenser shell condenser, convection heat exchange and cooling water, refrigerant gas absorption cooling condenses into liquid refrigerant liquid from the bottom of shell pipe flow. In order to enhance the heat exchange effect, the condenser copper tube usually adopts the low-finned tube. The inlet and outlet of the cooling water is located on the same side end cover. The two sides of the plate are divided into water floor. Force the cooling water to flow from the bottom to the top, and back and forth. The condenser shell is subjected to high cold media condensation pressure, especially when the cooling water is insufficient. The condensation pressure will reach the highest possible pressure, so the water condenser should be equipped with fusible safety plug.
In the cold dryer, the condenser is the largest part of the heat load, and its thermal load is equal to the sum of the heat absorption of the evaporator and the energy consumption of the compressor. Under the condition of cold drying machine, the heat load of the condenser is generally 1. 2 times.
The high and low pressure of refrigeration equipment is national standard. In normal work, the condensation pressure of R22 is no more than 1. It is advisable to 5 mpa. In practice, due to various reasons, the condensing pressure exceeds the situation. Condensing pressure too high will bring many ills of the refrigeration system (for person, the most obvious one is directly dew point rise), long-term operation under high condensing pressure, affect the service life of the compressor. The cold drying machine has high pressure protection device.
The reason for the high pressure of water condenser is: the water temperature is not enough, the water temperature is too high; The heat transfer area of the condenser is small; The air is immersed in the refrigerant system (caused by the rupture of the evaporator copper tube); The volume of the condenser shell is small, and the memory refrigerant liquid USES effective heat transfer area to reduce or the cold media fill too much; The water condenser is used for a long time. Scale of water side surface of copper tube; The opening degree of the automatic water regulating valve is small or damaged; The freezing oil enters the refrigeration system; The cooling water is not reasonable and the cooling water is backwater. There are blockages in the cold media channels or components (drying filter, solenoid valve, capillary, etc.); The loading of the refrigerator is too heavy. Raise the evaporation pressure, pull up the condensation pressure.
The reasons for the high condensation pressure of the air cooled condenser are: the environment temperature is high or the ventilation is bad; The surface area of the condenser is dust and dirt; The load of the cold dryer is too large; The air infiltration system; The heat transfer area of the condenser is not enough; The cooling fan is small; The installation position of the cold and dry hunger is not correct (such as proximity to the heat source, direct sun drying, the spacing between the cold and dry machine is too close, etc.); The pressure switch of the control fan is improper or damaged; There are blockages in the cold media channels or components; The heat transfer area is reduced by excessive filling of the cold media.
The reasons for the low condensation pressure of condenser are: too much water cooling or too low water temperature; The ambient temperature is too low; The pressure switch of the control fan or the automatic water regulating valve that controls the cooling water is improperly set or damaged; The amount of cold media is too small; There are leakage points in the refrigerant pipeline or components; The load of the cold dryer is too small.
Generally speaking, the condensing pressure slightly lower on the person and the refrigeration system operation, there is no greater impact, but the condensing pressure is too low to cause a decline in evaporating pressure sometimes, causes the evaporator frosting appear even compressor "liquid compression", this is the need to prevent.
What should be paid attention to when installation of air - cooled chiller? Air-cooled type person due to the heat dissipation effect than water-cooling person, therefore, when installation should pay attention to the following points: (1) shall be installed in ventilated place, before and after the condenser may have affect the ventilation barriers; Don't put it in the open air to avoid direct sunlight and affect the heat transfer effect. In the case of multi-dust, the filter screen should be set for easy cleaning without affecting the ventilation. There should be no heat source near the refrigerator, for example, with the air compressor; When a few typhoon cold dry machine coexist in a room, the cold dryer should be arranged horizontally, avoid mutual influence.
Daily maintenance points of air-cooled chillers: the dust accumulation on the surface of the condenser is often blown by air lance. Keep the automatic drain off the drain.
The function of water regulating valve is to control the opening degree of water regulating valve by using the change of cold medium condensation high pressure in refrigeration system. In order to adjust the cooling water volume, when the condensing pressure is high, the opening degree becomes larger and the cooling water volume increases. This will ensure the stability of the refrigeration system.
