【摘要】：隨著經濟的發(fā)展,環(huán)境保護和能源危機已成為世界關注的焦點,因此開發(fā)利用可再生能源具有非常重要的現實意義。我國是農產品生產、消費大國,但冷藏運輸上損耗也很嚴重。果蔬預冷是冷鏈中的重要環(huán)節(jié),將新鮮的果蔬在第一時間預冷可以最大程度上保證其品質。由于傳統(tǒng)的預冷庫都需要消耗電能,因而制約了其在田間地頭上的應用。 目前我國大多數果蔬在采摘后都不經預冷而直接運輸或銷售,因此果蔬的品質受到了嚴重的影響。如果以太陽能作為果蔬產地預冷庫的能源動力,則是既能提高果蔬貯藏品質,又可以采用環(huán)保能源的完美結合。 文中綜合國內外對太陽能吸附式制冷技術的研究現狀,以活性炭-甲醇為工質對,分別采用真空集熱管—水冷集熱吸附床和平板—自然冷卻集熱吸附床進行研究,對間歇和連續(xù)制冷循環(huán)方式進行了數值計算和相關實驗。 根據相關計算搭建了實驗臺,設計了真空管集熱吸附床、平板集熱吸附床及配套冷凝器、蒸發(fā)器和節(jié)流裝置。并對吸附床傳熱傳質、裝置的便捷性和牢固性等方面提出了一些改進。 通過對集熱吸附床的數值計算與分析,得出吸附床內溫度、吸附劑的吸附速率隨時間的變化關系。在日太陽最大輻射強度為790W/m2且其強度按正弦變化的條件下,計算出平板型吸附式制冷系統(tǒng)制冷系數COPref為0.594,真空管系統(tǒng)的COPref為0.517,脫附結束時平板系統(tǒng)內殘留甲醇占全部甲醇的百分比為6.3%,真空管為3.8%。 利用實驗裝置進行了三組實驗：其一是平板系統(tǒng)自然冷卻間歇式制冷,其二是真空管系統(tǒng)水冷間歇式制冷,其三是真空管系統(tǒng)水冷連續(xù)式制冷。實驗測出在蒸發(fā)溫度為0℃,冷凝溫度為40℃的工況下,平板系統(tǒng)間歇式制冷的太陽能制冷系數COP值為0.109～0.118；真空管系統(tǒng)間歇式制冷的太陽能制冷系數COP值為0.095～0.102；真空管系統(tǒng)連續(xù)式制冷的太陽能制冷系數COP值為0.105～0.110。將吸附床溫度的實驗結果和數值計算結果進行了比較,驗證了所建立模型的準確性。 分析了太陽能吸附式預冷庫技術性能,客觀地指出存在的問題,并對以后工作提出了建議。
[Abstract]:With the development of economy, environmental protection and energy crisis have become the focus of the world's attention, so the development and utilization of renewable energy has a very important practical significance. Our country is agricultural product production, consumption big country, but refrigerated transportation is also very serious. Pre-cooling of fruits and vegetables is an important part of cold chain, and the quality of fresh fruits and vegetables can be guaranteed to the greatest extent by pre-cooling fresh fruits and vegetables in the first time. The application of precooled storage in the field is restricted because of the need to consume electric energy. At present, most fruits and vegetables in our country are transported or sold directly without pre-cooling after picking, so the quality of fruits and vegetables is seriously affected. If solar energy is used as the energy power of fruit and vegetable production area, it can not only improve the storage quality of fruits and vegetables, but also adopt the perfect combination of environmental protection energy. In this paper, the research status of solar energy adsorption refrigeration technology at home and abroad is summarized. The vacuum collector tube water cooled adsorption bed and flat plate natural cooling collector adsorption bed are used to study the adsorption bed with activated carbon methanol as working medium. The batch and continuous refrigeration cycles were numerically calculated and related experiments were carried out. According to the relevant calculation, the experiment bench was built, and the vacuum tube heat collecting adsorption bed, flat plate heat collecting adsorption bed and matching condenser, evaporator and throttling device were designed. Some improvements on heat and mass transfer of adsorption bed, convenience and fastness of the device are put forward. Through the numerical calculation and analysis of the adsorption bed, the relationship between the temperature in the adsorption bed and the adsorption rate of the adsorbent with time is obtained. Under the condition that the maximum solar radiation intensity is 790W/m2 and its intensity varies according to sinusoidal, the refrigeration coefficient COPref of plate adsorption refrigeration system is 0.594, and the COPref of vacuum tube system is 0.517. At the end of desorption, the percentage of residual methanol in the plate system was 6.3% and the vacuum tube was 3.8%. Three groups of experiments were carried out by using the experimental device: one is the natural cooling intermittent refrigeration of the flat panel system, the other is the water-cooled intermittent refrigeration of the vacuum tube system, and the third is the water-cooled continuous refrigeration of the vacuum tube system. Under the condition of evaporation temperature 0 鈩，

本文編號：2369959