本文選題：太陽能制冷　切入點：吸收式制冷　出處：《上海交通大學》2015年博士論文

【摘要】：太陽能吸收式制冷是一項環(huán)保節(jié)能的制冷技術,是太陽能制冷的重要研究方向。太陽能吸收式制冷系統(tǒng)主要由太陽能集熱器和制冷機組成,大部分使用溴化鋰-水吸收式制冷機作為冷量輸出單元。其中太陽能集熱器提供熱源的溫度會隨著時間的變化而變化,并只能在晴天提供熱源,具有不穩(wěn)定性和間隙性。吸收式制冷機則需要溫度穩(wěn)定的熱源,機組COP隨熱源溫度變化不大,所以吸收式制冷機與太陽能集熱器的組合存在一些不匹配問題。本文從能量流動角度分析了這些不匹配問題,主要有太陽能間隙性帶來的需要額外熱源輸入問題,和太陽能不穩(wěn)定性帶來的能源品位浪費問題。針對這兩個問題本文進行了以下研究并得出相關結論:(1)由于太陽能具有間隙性,太陽能吸收式制冷系統(tǒng)大多需要和化石燃料互補以確保系統(tǒng)連續(xù)運行。由于化石燃料燃燒所得能量品位高,采用單效溴化鋰-水吸收式制冷機為冷量輸出單元的系統(tǒng)在使用額外熱源時,存在很大的能源品位浪費。這種品位浪費可以通過采用單/雙效吸收式制冷機來解決,即系統(tǒng)在太陽能驅動下以單效吸收式制冷模式運行,在燃氣驅動下以雙效吸收式制冷模式運行。本文對一個太陽能/燃氣驅動單/雙效吸收式供能系統(tǒng)進行了實地運行分析,得到了系統(tǒng)一整年的運行情況。系統(tǒng)的兩種模式均可以穩(wěn)定運行,太陽能驅動模式可以達到0.62的COP,相比純燃氣驅動系統(tǒng)整年燃氣消耗量減少50.3%。(2)針對低溫太陽能熱源的不穩(wěn)定性,提出使用低溫太陽能變效(0.n效)吸收式制冷循環(huán)。該吸收制冷循環(huán)是在半效循環(huán)的基礎上將內部換熱結構改為外部換熱結構而得到,通過改變中壓蒸發(fā)器冷量分流比例可以得到從半效到單效的變效制冷。基于模型對該制冷方式進行了計算,在蒸發(fā)溫度5oC,冷卻水溫分別為32oC和40oC的工況下,循環(huán)可工作熱源范圍分別為83.5oC-110oC和104oC-127oC,相比單效循環(huán)先比工作溫度范圍分別擴大了2倍和6倍,而COP則在0.3到0.7之間變動。(3)針對中溫太陽能熱源的不穩(wěn)定性,提出使用具有更高經濟性的中溫太陽能變效(1.n效)吸收式制冷循環(huán)。為了得到1.n效吸收式制冷循環(huán),對吸收式制冷循環(huán)進行了理論分析和構建方式分析,將循環(huán)構建方式主要歸納為溶液回路外的熱質耦合和溶液回路內的熱質耦合。傳統(tǒng)循環(huán)對熱源適應性差是因為這些循環(huán)采用回路外耦合構成,循環(huán)被這些耦合鎖死所以在熱源溫度變化時無法做出相應改變。通過分析得到吸收循環(huán)構建的幾個基本準則。針對中溫太陽能利用,依據這些準則對1.5效系統(tǒng)進行基于回路外耦合的構建,得到8種新型1.5效吸收式制冷循環(huán)形式。再通過濃度變化延展增加回路內耦合過程,提高循環(huán)自由度,得出另外4種循環(huán)方式。其中一種即為所需要的中溫變效(1.n效)循環(huán)。(4)對以溴化鋰-水為工質的中溫變效(1.n效)循環(huán)進行理論分析。循環(huán)將高壓發(fā)生器產生蒸汽分為兩部分,一部分進入冷凝器,一部分進入高壓吸收器。進入高壓吸收器的蒸汽降低了溶液濃度和平衡溫度,此時即便高壓冷凝熱溫度沒有雙效循環(huán)高,也可以驅動溶液的發(fā)生過程,從而達到了對高壓冷凝熱的回收。根據發(fā)生溫度不同,可以通過調整進入高壓吸收器溶液流量來改變循環(huán)。通過建模計算,在85 oC到150 oC之間的發(fā)生溫度下,循環(huán)可以得到0.75到1.08的COP。(5)基于1.n效循環(huán)對1.n效溴冷機進行設計和實驗分析。通過計算,確定發(fā)生溫度125oC、冷凝溫度40 oC、吸收溫度35 oC和蒸發(fā)溫度5 oC的設計工況。對所加工的50kW機組測試得到機組可以在95 oC到120 oC的發(fā)生溫度工況下得到0.69到1.08的COP。根據實驗數據和理論計算數據的對比可以得知,實驗COP和相應工況下理論計算COP的平均誤差為7.3%。(6)基于實驗數據得到了1.n效溴冷機的人工神經網絡模型。模型以熱源進口溫度、冷卻水進口溫度、冷水進口溫度和所需冷量為輸入參數,以冷水出口溫度和冷卻水出口溫度為輸出參數�；赥RNSYS平臺建立CPC集熱器和1.n效溴冷機的模塊,并組建CPC驅動1.n效溴冷機的系統(tǒng),并進行模擬計算,對系統(tǒng)進行優(yōu)化計算。得到該太陽能制冷系統(tǒng)的制冷機在運行中可以達到1.1的瞬時COP和超過0.8的平均COP。
[Abstract]:Solar absorption refrigeration refrigeration technology is a green energy, is an important research direction of the solar refrigeration. Mainly by the solar collector and refrigerator solar absorption refrigeration system, most of the use of LiBr-H2O as cooling output unit. The solar collector and the temperature of the heat source will provide change over time, and can provide heat in sunny days, with instability and gap. Absorption refrigerating machine requires heat source temperature stable, little change in unit COP with heat source temperature, so the combination of absorption chiller and solar collector has some matching problem. This paper analyzes these problems do not match from the angle of energy flow, mainly caused the need for additional clearance solar heat source, the problem of energy waste and solar grade bring instability to the. Two problems this paper carried out the following research and draw relevant conclusions: (1) because the solar energy is intermittent, solar absorption refrigeration system mostly fossil fuels and complementary systems to ensure the continuous operation. Due to the burning of fossil fuels the energy of high grade, the single effect lithium bromide - water absorption chiller for cooling output unit in the use of additional heat source, there is a big waste of energy grade. The waste grade can be achieved by the use of single / double effect absorption refrigerating machine to solve, namely system driven by solar energy on the single effect absorption refrigeration mode operation in gas driven by double effect absorption refrigeration operation mode. In this paper a solar / gas driven single / double effect absorption type energy supply system for field operation analysis, get the operation situation of the system for a whole year. Two modes of system can be stable operation, solar energy The driving mode can reach 0.62 COP, compared with the pure gas drive system year gas consumption reduced 50.3%. (2) for low temperature solar heat instability, put forward using low temperature solar effect (0.n effect) absorption refrigeration cycle. The absorption refrigeration cycle is based on internal circulation half effect heat exchanger structure will change the structure of external obtained by changing the medium pressure evaporator cooling capacity shunt ratio can be obtained from the half effect to effect refrigeration. The single effect model to calculate the refrigeration mode based on 5oC in evaporation temperature, cooling water temperature are respectively 32oC and 40oC under the condition of circular working range of heat sources were 83.5oC-110oC and 104oC-127oC. Compared with the single effect cycle than the first temperature range were expanded by 2 times and 6 times, while COP changes between 0.3 to 0.7. (3) according to the temperature of the solar heat instability makes has higher Temperature of the solar economy variable effect (1.n effect) absorption refrigeration cycle. In order to get the 1.n effect absorption refrigeration cycle, the absorption refrigeration cycle are analyzed by theoretical analysis and construction methods, construction methods are summarized for the circulating heat coupling solution loop heat and mass coupling and loop. The traditional solution cycle of heat adaptability is because these cycles with loop coupling, the coupling loop is locked so in the heat when the temperature changes to make the corresponding change. Through the analysis of several basic principles of circular construction to be absorbed. According to the temperature of the solar utilization, on the basis of the criterion of 1.5 effect system construction based on loop coupling. Get 8 new 1.5 effect absorption refrigeration cycle. To increase the coupling process of the loop through the change of the concentration extension, improve circulation degree of freedom, the other 4 cycles. A temperature change is in effect required (1.n effect) cycle. (4) for lithium bromide - water as refrigerant temperature variable effect (1.n effect) cycle were analyzed. The loop will produce steam high pressure generator is divided into two parts, one part enters the condenser part in high pressure absorption. The steam into the high-pressure absorber reduces the solution concentration and the equilibrium temperature, even if high-pressure condensation heat temperature without double cycle high, can also occur process driven solution, so as to achieve the recovery of high pressure condensing heat. According to the different temperature, can adjust the flow to change into a high-pressure absorber solution by modeling cycle. In the calculation, 85 oC to 150 oC between the temperature, cycle can get 0.75 to 1.08 COP. (5) 1.n effect cycle design and experimental analysis on 1.n effect based on lithium bromide refrigerator. Through calculation, the temperature of the condensing temperature 125oC, 4 0 oC, 35 oC design condition absorption temperature and evaporation temperature of 5 oC. The test of 50kW units are set in the processing of 95 oC to 0.69 to 1.08 COP. according to the experimental data and the theoretical calculations of the contrast can be learned the cause of temperature of 120 oC, the average error calculation of COP COP and the corresponding experimental conditions under the theory of 7.3%. (6) based on the experimental data obtained by the artificial neural network model 1.n. Effect of lithium bromide refrigerator to the heat source inlet temperature model, inlet temperature of cooling water, cooling water inlet temperature and required cooling capacity as input parameters, the cold water outlet temperature and the cooling water outlet temperature as output parameters. TRNSYS platform based CPC set heat exchanger and 1.n effect LiBr absorption chiller module based on the system and the formation of CPC driven 1.n effect LiBr absorption chiller, and simulated, to optimize the system. The calculation of refrigeration machine solar cooling system in the operation can be Up to 1.1 of the instantaneous COP and an average of more than 0.8 of the COP.

【學位授予單位】：上海交通大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TB657

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