Study On Fluid Flow And Heat Transfer In A Mini Channel Tube-in-tube Heat Exchanger

Tube heat exchanger is widely used as a device with excellent heat transfer performance in many energy systems. Due to the rise in raw materials price, the development of more compact and efficient heat exchanger is becoming a hot spot of current research. Under this background, this paper designs a tube heat exchanger with tubes in 4 mm and analysis the flow and heat transfer characteristics of the heat exchanger by using experimental and numerical simulation methods. Meanwhile, this paper does some researches on the distribution of the mini channels. Then do some experiments to compare it with coaxial pipe heat exchanger. The main works are briefly reviewed as follows:With existing coaxial pipe heat exchanger performance and 20mm outside diameter as an index, this paper simulates the flow and heat transfer characteristics of the heat exchanger with tubes in 4mm and 5mm respectively. Analyze the performance of the heat exchanger with mini tubes according to the simulation results. The simulation results show that:When heat exchanger tube size decreases from 5 mm to 4mm, the tube adds 3.66% copper consumption and more pressure loss. But heat transfer area adds 6.63% and the heat transfer coefficient improves. In generally its heat transfer performance can be enhanced.In order to get the best spaces between channels when use 4mm mini channels, this paper studies the heat transfer performance and temperature distribution of a cross section in different spaces between mini channels. The spaces are 5mm,5.5mm,6mm, 6.5mm and 7mm. The comparative studies show that:The best space between mini channels is 6.5mm. In this space, the heat exchanger has best heat transfer performance.To verify the correctness of the numerical simulation analysis, a test platform for the heat transfer performance of the mini channel tube heat exchanger is designed and set up. It studies the fluid flow and heat exchanger performance of the heat exchanger with water as working substance. Calculate the heat transfer coefficient and tube side pressure drop in different operating conditions. At last, compare the experimental results with the numerical simulation results.Compare the mini channel tube heat exchanger with coaxial pipe heat exchanger by experiments. Analyze the different heat transfer performance between them. Verify the meaning of study and application of mini channel tube heat exchanger and provide a direction for future researches.