The elbow thermosyphon: An experimental investigation of its evaporative behaviour

摘要

The thesis presents the results of an experimental investigation of an evaporative, elbow thermosyphon under low pressure conditions. Emphasis is placed in three areas: firstly, the effect of filling charge on the heat transfer rate; secondly, the effect of tube geometry on the heat transfer rate; finally, the effect of tube orientation on the heat transfer performance.;Reference values of the thermosyphon parameters are chosen for comparing with the results of each test. They are: L$sb{rm H}$/D = L$sb{rm C}$/D = 20 and v$sb{rm R}$ = 35%. For all the experiments, the temperature difference between evaporator and condenser is 0 $<$ T$sb{rm H}$-T$sb{rm C} <$ 100 K. The experimental range of filling charge is from 10% to 75% with a fixed tube geometry. The experiments of tube geometry cover the range $rm 10le Lsb{H}/Dle 40$ and $rm 10le Lsb{C}/Dle 40$ while the filling charge was fixed at 35%. For the experiments on tube orientation, due to symmetry, the ranges covered are: $0lephisb{rm t}lepi/2$ and $0lephisb{rm r}lepi/2$ with the fixed reference values of tube geometry and filling charge.;The data reveal the hydrodynamic and thermal behavior of the thermosyphon for a given filling charge, tube length, and inclination. Explanations of the heat transfer behaviour observed are given in each chapter. The optimum values, such as filling charge and inclination, are given for the purpose of application.