Heat and hydrodynamic calculation of tube-in-tube heat-exchanger

Abstract
The article deals with a calculation of tube-in-tube heat-exchangerwith capped end where cryogen from internal pipe is vaporized due to addition of heat from an object being cooled through the end, and the vapor is removed through circular duct between external and internal tube. The method is that the device is subdivided into several sections along the cryogen flow which are small enough to meet the desired calculation accuracy. Then the set of heat, temperature and pressure equations for every section are solved. Heat flow at the end and heat transfer to the external tube from the environment is set as the boundary conditions. The equations are solved by the method of simple iterations. Calculation results for different values of heat-exchanger parameters, heat transfer medium saturation pressure and heat load at the heat exchanger end, and heat gain from the environment are given.