【摘要】：近年來，隨著國家“節(jié)能減排”基本國策的推行，居民節(jié)能環(huán)保的意識也得到空前提高，燃氣熱水器行業(yè)亦向著“高效、智能”新方向轉型、升級。冷凝式燃氣熱水器充分利用傳統(tǒng)熱水器的排煙余熱，大幅提升了其熱效率，，具有巨大進步意義。目前，國內外研究大多偏重于對冷凝式燃氣熱水器的整體能效評估和分析，少有對冷凝器的性能進行單獨的測試、探究。此外，國內市場上的產品技術尚不成熟，節(jié)能效果也參差不齊，大多品牌產品實際熱效率尚維持在90%~100%之間。究其原因是：為傳統(tǒng)燃氣熱水器增設冷凝器時，沒有全面整合和優(yōu)化匹配兩級換熱工況；并且對于冷凝器設計也沒有適用性較強的計算模型，或具有指導意義的換熱優(yōu)化方案。 本文以實驗為基礎，參照《家用燃氣快速熱水器》GB6932-2001標準要求，設計并搭建了熱水器測試平臺。選定市售JSQ21-QL12LJW型冷凝式燃氣熱水器作為實驗樣本，對其冷凝器進行測量、繪制、計算、性能測試；再根據傳熱學、工程熱力學、流體力學等基礎理論，以對流換熱、凝結換熱兩大理論為核心，對該冷凝器進行理論計算、分析，得出該冷凝器的理論換熱參數及換熱性能分析解；最后對比理論分析和實際測試的結果，構建出對同類型冷凝器換熱性能有適用性、指導性的換熱模型。 根據以上實驗研究，主要結論如下： ①樣本熱水器的冷凝段水溫升為2~4，燃氣燃燒熱量利用率提高了約8%~14%（以燃氣低熱值為基準）。 ②冷凝換熱所占比例客觀影響著熱水器總熱效率的高低。在額定水流量范圍內冷凝換熱所占比例在10.5%~12.5%區(qū)間，是最優(yōu)化熱分配方案。 ③熱負荷、水流量、煙氣冷凝溫差是影響冷凝水量的重要因素，冷凝水量隨著、、的增大而呈單調增加。 ④煙氣的水蒸氣冷凝率隨冷凝段熱負荷增大而呈持續(xù)上升狀態(tài)；相同條件下，水流量越大，冷凝率也會越高。冷凝器的凝結工況上限是60%~65%。 ⑤冷凝器效率與總熱效率客觀存在規(guī)律性。在全負荷范圍內，處于65%~75%區(qū)間，總熱效率最高，即是冷凝器的最優(yōu)化工況。 ⑥本文采用努謝爾特膜狀凝結換熱分析解結合對流換熱雷諾類比律，構建出了混合換熱模型，進一步推出實驗關聯(lián)式。經實驗結果對比驗證并加入修正因子之后，該計算模型在一定程度上對同類型熱水器冷凝器的復合換熱性能設計、計算具有適用性。
[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.
【學位授予單位】：重慶大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU822

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