[Mechanical Equipment Technology Edition] Daily Question 201801018: Common Faults in Refrigeration Systems (7.1)
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This post was last edited by YORK Industrial Refrigeration on 2018-1-20 at 09:24. Starting from now, in order to enhance communication among users, a 【Daily Question】 campaign has been launched on the Mechanical Equipment Technology forum; we hope everyone will participate actively to progress and improve together! ! ! Rewards: 3 wealth points for active participation, 10-15 wealth points for correct answers. This question is valid for two days; no score will be assigned if more than two days pass. In a refrigeration system, what are the factors that affect the heat exchange efficiency of the condenser? Here, we will analyze only the principle of the most common horizontal condensers: Water exchanges heat with the refrigerant through the heat exchange tubes. Therefore, we will examine this from three aspects: the water side, the refrigerant side, and the heat exchange tubes. For water: scale, flow rate, and inlet temperature. For heat exchange tubes: material (heat transfer coefficient) and shape (external threads). For the refrigerant: its saturated temperature, liquid level (area in contact with the copper tubes), and flow rate. ============================== Premium promotions: Mechanical equipment——York screw compressors: maintenance procedures https://bbs.hcbbs.com/thread-1806833-1-1.html Mechanical equipment——York Quinton control centers: upgrades https://bbs.hcbbs.com/thread-1804837-1-1.html Mechanical equipment——GEA Grasso screw compressors: major repairs https://bbs.hcbbs.com/thread-1800467-1-1.html Mechanical equipment——British HOWDEN screw compressors: disassembly and maintenance https://bbs.hcbbs.com/thread-1832529-1-1.html Mechanical equipment——Japanese MYCOM screw compressors: disassembly and maintenance https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=
Heat exchange area, fluid flow velocity, flow rate
1. Surface heat transfer coefficient during refrigerant condensation 2. Surface heat transfer coefficient of the cooling medium 3. Thermal conductivity of the material used for the heat exchanger 4. Degree of contamination of the heat exchanger surface by oil and scale
The factors that affect the heat transfer efficiency of a condenser are the heat transfer coefficient K, the heat transfer area S, and the average temperature difference △t.
1. Thermal conductivity of the material, 2. Contact area between the heat transfer medium and the heat exchanger. 3. Flow velocity of the fluid
On the water side inside the tubes, scaling and corrosion occur due to water quality issues; leaks result from problems in the equipment’s manufacturing process; and the reduced service life is caused by tube wall thickness not meeting the required standards.
For a given condenser, whose heat exchange area is fixed, the main factors affecting its heat exchange efficiency are: 1. The flow rate of the cooling medium passing through the condenser; 2. The temperature of the cooling medium flowing through the condenser; 3. The degree of dirt on the surface of the condenser
Factors such as the heat transfer coefficient on the refrigerant side, surface fouling, and the heat transfer coefficient of the medium being cooled
Factors affecting the heat transfer efficiency of condensers: 1. Heat transfer area (with ribs or fins) and material of the heat exchange tubes; 2. Refrigerant flow rate and direction; 3. Non-condensable gases; 4. Oil content; 5. Condenser design and type; 6. Cooling medium
In a refrigeration system, what are the factors that affect the heat exchange efficiency of the condenser? Answer: 1. It is the thermal conductivity of the heat exchanger material ； 2. Heat transfer medium and contact area with the heat exchanger ； 3. Flow velocity of the fluid ；
One is the thermal conductivity of the heat exchanger material, and the other is the contact area between the heat transfer medium and the heat exchanger. 3. The flow velocity of the fluid.