冷凝式燃气热水器的冷凝器性能研究

发布时间：2018-08-09 09:46

【摘要】：近年来，随着国家“节能减排”基本国策的推行，居民节能环保的意识也得到空前提高，燃气热水器行业亦向着“高效、智能”新方向转型、升级。冷凝式燃气热水器充分利用传统热水器的排烟余热，大幅提升了其热效率，，具有巨大进步意义。目前，国内外研究大多偏重于对冷凝式燃气热水器的整体能效评估和分析，少有对冷凝器的性能进行单独的测试、探究。此外，国内市场上的产品技术尚不成熟，节能效果也参差不齐，大多品牌产品实际热效率尚维持在90%~100%之间。究其原因是：为传统燃气热水器增设冷凝器时，没有全面整合和优化匹配两级换热工况；并且对于冷凝器设计也没有适用性较强的计算模型，或具有指导意义的换热优化方案。本文以实验为基础，参照《家用燃气快速热水器》GB6932-2001标准要求，设计并搭建了热水器测试平台。选定市售JSQ21-QL12LJW型冷凝式燃气热水器作为实验样本，对其冷凝器进行测量、绘制、计算、性能测试；再根据传热学、工程热力学、流体力学等基础理论，以对流换热、凝结换热两大理论为核心，对该冷凝器进行理论计算、分析，得出该冷凝器的理论换热参数及换热性能分析解；最后对比理论分析和实际测试的结果，构建出对同类型冷凝器换热性能有适用性、指导性的换热模型。根据以上实验研究，主要结论如下： ①样本热水器的冷凝段水温升为2~4，燃气燃烧热量利用率提高了约8%~14%（以燃气低热值为基准）。 ②冷凝换热所占比例客观影响着热水器总热效率的高低。在额定水流量范围内冷凝换热所占比例在10.5%~12.5%区间，是最优化热分配方案。 ③热负荷、水流量、烟气冷凝温差是影响冷凝水量的重要因素，冷凝水量随着、、的增大而呈单调增加。 ④烟气的水蒸气冷凝率随冷凝段热负荷增大而呈持续上升状态；相同条件下，水流量越大，冷凝率也会越高。冷凝器的凝结工况上限是60%~65%。 ⑤冷凝器效率与总热效率客观存在规律性。在全负荷范围内，处于65%~75%区间，总热效率最高，即是冷凝器的最优化工况。 ⑥本文采用努谢尔特膜状凝结换热分析解结合对流换热雷诺类比律，构建出了混合换热模型，进一步推出实验关联式。经实验结果对比验证并加入修正因子之后，该计算模型在一定程度上对同类型热水器冷凝器的复合换热性能设计、计算具有适用性。
[Abstract]:In recent years, with the implementation of the basic national policy of "energy saving and emission reduction", the awareness of energy saving and environmental protection of residents has been improved unprecedented, and the gas water heater industry has also been transformed and upgraded in the new direction of "high efficiency and intelligence". Condensed gas water heaters make full use of the exhaust heat of traditional water heaters and greatly improve their thermal efficiency. At present, most researches at home and abroad focus on the evaluation and analysis of the overall energy efficiency of condensed gas water heaters, and there are few separate tests on the performance of condensers. In addition, the domestic market product technology is not mature, energy efficiency is also uneven, most of the actual thermal efficiency of brand products are still maintained at 90% or 100%. The reason is that when the condenser is added to the traditional gas water heater, there is no comprehensive integration and optimization matching for the two-stage heat transfer condition, and there is no suitable calculation model for the condenser design, or a guiding heat transfer optimization scheme. Based on the experiment, the test platform of water heater is designed and built according to GB6932-2001 standard. The commercial JSQ21-QL12LJW condensate gas water heater is selected as the experimental sample to measure, draw, calculate and test the performance of the condenser, and then according to the basic theories of heat transfer, engineering thermodynamics, hydrodynamics and so on, the convection heat transfer is used. The condensation heat transfer theory is the core of the condenser. The theoretical calculation and analysis of the condenser are carried out, and the theoretical heat transfer parameters and heat transfer performance of the condenser are obtained, and the results of the theoretical analysis and the actual test are compared. A suitable and instructive heat transfer model for the same type of condenser was constructed. According to the above experimental research, The main conclusions are as follows: 1 the water temperature of the condensing section of the sample water heater rises to 2? 4, and the utilization rate of combustion heat increases by about 8% (based on the low calorific value of gas). 2 the proportion of condensation heat transfer affects the heat objectively. The total thermal efficiency of the water heater. In the range of rated water flow, the proportion of condensation heat transfer is in the range of 10.5% or 12.5%, which is the optimum heat distribution scheme. 3 the heat load, water flow rate and flue gas condensation temperature difference are the important factors affecting the condensing water quantity. The condensation rate of flue gas increases with the increase of the heat load of the condensing section, and under the same conditions, the higher the water flow rate is, the higher the condensation rate will be. The upper limit of condenser's condensing condition is 60 / 65. 5 there are rules between condenser efficiency and total thermal efficiency. In the range of full load, the total heat efficiency is the highest in the range of 65% and 75%, which is the optimum condition of the condenser. 6 the solution of Nusselt membrane condensation heat transfer and the Reynolds analogy law of convection heat transfer are used in this paper. The mixed heat transfer model was constructed, and the experimental correlation was deduced. After the experimental results are compared and the correction factor is added, the calculation model is applicable to the design of the composite heat transfer performance of the condenser of the same type water heater to a certain extent.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU822

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