| It is widely known that energy is the economic lifeline of a country and the problem of energy assumption is one of the most important problems in our society. So energy conservation must be an important strategic way to implement sustainable development in our country. As building energy consumption accounts for large proportion in total energy consumption, how to reduce the building energy consumption has become a problem urgently to be solved. Heat-source towers are energy utilization devices, which are able to extract heat from ambient air or industrial waste gas.The research about heat-source towers is based on the methods of the theory of cooling towers. And it hasn’t been a long time after heat-source tower was defined, so the theoretical research and practical application of a heat-source tower is not very mature. And in the previous study, heat-source tower performance calculations are usually performed numerically, and there are almost no analytical solutions for an engineering preliminary calculation of a heat- source tower. And the solutions which have been proposed can only calculate one type of heat- source tower.In order to solve the problems above, firstly, the characteristics of the heat-and mass-transfer process in a heat source tower are analysed in detail, and the differences of heat- and mass-transfer mechanism between a heat-source tower and a cooling tower are summarized. Then a non-dimensional mathematical model for the description of a heat-source tower is presented in this paper based on the evaporative cooling devices model and the cooling tower model presented by Boris Halasz. This non-dimensional mathematical model can be used to calculate parallel-flow, counter-flow and cross-flow heat-source tower. Finally, the feasibility analysis of applying a heat-source tower to recover industrial low temperature heat is carried out.Firstly, the internal heat- and mass-transfer mechanism of a heat-source tower is analyzed in detail. And the differences of heat- and mass-transfer mechanism between a heat-source tower and a cooling tower are summarized, that is, different latent heat transfer, different water-side heat transfer resistance, different heat and mass transfer direction, different physical property of circulating liquid, and so on.Secondly, using the model presented in this paper, the parallel-flow and counter-flow heat-source towers can be calculated analytically, and cross-flow heat-source tower can be calculated only by numerical methods. After calculation, the air and water states at any horizontal plane along the height within a heat-source tower can be determined in detail and the air outlet parameters are obtained by simple expressions. By comparing to the experimental data published, it can be seen that the solutions of the model have a good agreement with the experimental data, so it is concluded that the non-dimensional model can be used to calculate the parameters of a heat-source tower.In the end, heat-source towers using for recover industrial low temperature waste heat are analyzed. Take an industrial application for example, using the heat-source tower for recycling the waste heat in the return air can meet the heat load of the inlet air of the mine. And it is shown that the inlet fresh air temperature of intake shaft can be heated to over 2℃ in local normal weather, and in the weather of the lowest temperature it can be heated to 2℃. |
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