condition. Clea 228 Exercie OF WORKSTATION AND TOOLS: Return the refrigeration s
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condition. Clea 228 Exercie OF WORKSTATION AND TOOLS: Return the refrigeration system to its proper respective places MAINTENANCE workstaioe and reurn all tools to their relationship of a typical air-cooled necessary for your additional sheer of paper if more spac is 5. Why must an air-cooled condenser be located where the air will not recirculate through it QUESTIONS 1. Name the three functions that a condenser performs 2. What is considered the highest temperature that 6. What does the compressor amperage do when the the discharge gas should reach upon leaving the compressor? head pressure rises? 7. What would the symptoms be if a condenser had 3. What may be used on an air-cooled condenser with a fan to prevent the head pressure from becoming too low in mild weather? two fan motors and one stopped running? 8. What is the purpose of the fins on the condenser? 4. What are the system results of an air-cooled condenser operating with a head pressure that is too low? 9. What materials are typical refrigeration condensers made of?Explanation / Answer
1:- The three main functions of the condenser are:
i). Desuperheating. The first passes of the condenser desuperheat the discharge line gases. This prepares the high-pressure, superheated vapors coming from the discharge line for condensation, the phase change from vapor to liquid.
ii). Condensing - one of the main functions of the condenser is to condense the refrigerant vapor to liquid. Condensing is system dependent; it usually takes place in the lower two-thirds of the condenser. Once the saturation or condensing temperature is reached in the condenser and the refrigerant gas has reached 100 percent saturated vapor, condensation can take place - if more heat is removed.
iii). Subcooling - The last function of the condenser is to subcool the liquid refrigerant. Subcooling is defined as any sensible heat taken away from 100-percent-saturated liquid. Technically, subcooling is defined as the difference between the measured liquid temperature and the liquid saturation temperature at a given pressure. Once the saturated vapor in the condenser has phase changed to saturated liquid, the 100-percent-saturated liquid point has been reached.
2:- The limit to any compressor discharge temperature is 225 degrees F. If the discharge temperature gets higher than 225 degrees, the system may start to fail from worn rings, acid formations, and oil breakdown. Remember, if the discharge temperature is 225 degrees, the actual discharge valve will be about 75 degrees hotter. This will bring the actual compressor’s discharge valve to 300 degrees. It is a known fact that most oil may start to break down and vaporize at 350 degrees. If this occurs, serious overheating problems will happen.
3:- i) cycling the condenser fan. ii) controlling dampers in the air-stream through the condenser.
iii) flooding the condenser with refrigerant.
Also in applications that have a reciever a headmaster valve can be used to maintain head pressure.
4:- When refrigeration systems are exposed to low ambient conditions, the condensing pressure (head pressure) will fall. If the head pressure gets too low, the metering device will not have enough pressure drop across it to operate properly. The metering device will underfeed the evaporator and a low pressure will result in the evaporator. This can cause refrigeration systems to short cycle from the low-pressure control, opening prematurely. Also, once the refrigeration system is off, it may never turn back on again because the evaporator pressure may never reach the cut-in pressure of the low-pressure control. Condensing units that are exposed to low ambient conditions must have some sort of low ambient control installed on them to prevent their head pressures from falling too low.
5:- Air-cooled condensers should always be located in a well ventilated space. This is how the heated air may escape and be replaced by cooled air. Because of space requirements, air-cooled condensers are normally constructed with a relatively small face with several rows of tubing in depth. As the air is forced through the condenser, it absorbs heat, and the air temperature rises. Therefore, the efficiency of each succeeding row in the coil decreases, although coils up to eight rows in depth are frequently used.
6:- When the head pressure rises the amperage will rise beacuse it is doing more work and working harder.
As the head pressure rises, the compressor begans to work harder. What happens as a motor begans to work harder
7:- when a condenser has more than 1 fan, ! fan can be put in the lead & the other fan can be cycled off and on by temperature. this helps prevent pressure swings
8:- These air conditioner fins are a part of the condenser that assists heat in moving away from the air conditioner so that the heat disperses more quickly.
9:- stainless steel, copper and nickel
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