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Contact us
- Haining Jineng Solar Energy Industry Co., Ltd.
Add:NO.9 danjing Road Haining Economic Development Zone
Tel: 0086-573-87096288
Fax: 0086-573-87293344
Email:dixon@jinengsolar.com
- Structure and Principle
The heat pipe is hollow with the space inside evacuated, much the same as the solar tube. In this case insulation is not the goal, but rather to alter the state of the liquid inside. Inside heat pipe is a small quantity of purified water and some special additives. At sea level water boils at 1000C, but if you climb to the top of a mountain the boiling temperature will be less that 1000C. This is due to the difference in air pressure.
Based on this principle of water boiling at a lower temperature with decreased air pressure, by evacuating heat pipe, we can achieve the same result. The heat pipes have a boiling point of only 300C. So when it is heated above 300C, the water vaporizes. This vapour rapidly rises to the top of the heat pipe transferring heat. As the heat is lost at the condenser (top), the vapour condenses to form a liquid (water) and returns to the bottom of the heat pipe. And then repeat the process again.
- Quality Control
Material quality and cleaning is extremely important to the creation of a good quality heat pipe. If there are any impurities inside the heat pipe it will effect the performance. The purity of the copper itself must also be very high, containing only trace amounts of oxygen and other elements. If the copper contains too much oxygen or other elements, they will leach out into the vacuum forming a pocket of air in the top of the heat pipe. This has the effect of moving the heat pipe's hottest point (of the heat condenser end) downward away from the condenser. This is obviously detrimental to performance, hence the need to use only very high purity copper.
The heat pipe used in our solar collectors comprises two copper components, the shaft and the condenser. Prior to evacuation, the condenser is brazed to the shaft. Note that the condenser has a much larger diameter than the shaft, this is to provide a large surface area over which heat transfer to the header can occur. The copper used is oxygen free copper, thus ensuring excellent life span and performance.
Each heat pipe is tested for heat transfer performance and exposed to 300oC temperatures prior to being approved for use. For this reason the copper heat pipes are relatively soft. Heat pipes that are very stiff have not been exposed to such stringent quality testing, and may form an air pocket in the top over time, thus greatly reducing heat transfer performance.
