Study On High Efficient Air-water Direct Contact Heat Transfer Process And Equipment

It's very necessary to develop the use of reproducible and low quality energy under the actuality of the world's energy utilization. In this process, effective and high efficiency technology of using this kind of energy is needed. Air-water direct contact heat transfer in packing towers is an important and high efficiency form of heat transfer, and it's also an ideal way of low quality energy utilization. Much effort has been put on the study of the air-water direct contact heat transfer both in packing towers and cooling towers. But there has no research found abroad and at home on air-water direct contact heat transfer in packing towers using low quality energy such as seawater thermal energy as direct energy resources of air-condition systems.To study the process, propel and carry out the application of air-water direct contact heat transfer in packing towers, a pilot plant has been built and improved constantly according to the problems and needs newly occurred during the experiments process. Concretely, to optimize the distribution of the water, a water distributor was placed in the tower. And to get rid of the water drops in outlet air, a drip-air separator was placed in the air outlet pipe. What is more, to prevent the unanticipated air leak, a water-close section was added under the bottom of the tower.In most of the experiments, low heat transfer temperature differences (Ta-ti) and high hv (Volumetric Heat Transfer Coefficient) and hv (Volumetric Heat Transfer Velocity) values have been gotten which prove the high heat transfer efficiency and capacity of pilot equipment and this kind of equipments. Most of the hv values weget using the CMR packing range between 5000-35000 W/(m3 ) which are much higher than the results of a similar research done by a foreign scholar, and the value rises to 40000 W/(m) while using structured pacing even though the distribution of the water are not good enough. At the same time, the hv values of CMR packing range between 50-200kW/m3 and the structured packing reach 300 kW/ m3 althoughunder common water distribution state.After analysising the data obtained from several series of experiments, therelationships between operation parameters and hV, hV are found. Some of the relationships such as the linear relationship between water mass flow rate and hVaccord with other scholar's research results and other relationships are completely new. These new relationships included the logarithmic relationships between watermass flow rate and hV:hV=a1nL-b , the Exponential Decay and Boltzmannrelationships between h\ and water mass flow rate.Further more, the advantages of air-water direct contact heat transfer in packing equipment are clearly represented by being compared with high efficient indirect contact heat exchanger in the same circumstance. The former style has many advantages such as lower outlet air temperature, larger heat exchanging capacity, smaller size and less inlet water.At last, two air-conditioning application schemes using seawater or groundwater are brought forward. They are:a) Directly cooling and heating system by sea-waterb) Hybrid cooling and heating system of heat pump and direct contact heat transfer of sea-waterBoth these two schemes have high efficient and capacity of heat exchanging. Further more, two application systems of the first scheme are designed. One is the minitype system and the other is the District Heating and Cooling (DHC) system. Both of these two systems have higher COP values and lower running costs man common air-conditioning equipments or systems.