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送風(fēng)風(fēng)速對蘋果差壓預(yù)冷性能的影響
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“十二五”國家科技支撐計劃資助項目 (2013BAD19B04) 和歐盟FP7資助項目(PIRSES-GA-2013-612659)


Effect of Air-inflow Velocity on Cooling Efficiency during Forced-air Precooling of Apples
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    摘要:

    收后果蔬的及時預(yù)冷已成為供應(yīng)商一項必備的增值業(yè)務(wù),提高其預(yù)冷均勻性及預(yù)冷速率不僅可以延長果蔬貨架期、提高預(yù)冷吞吐量,整體冷鏈物流的經(jīng)濟(jì)效益也可得到直接保證與提升。以富士蘋果2層瓦楞紙包裝箱為研究對象,建立箱體、襯墊及果品的三維實體模型,將果品呼吸熱、表面蒸發(fā)熱、冷凝熱及對流傳熱作為果品區(qū)域內(nèi)部熱源,利用CFD模擬預(yù)冷過程中不同送風(fēng)速度下箱體內(nèi)部溫度分布情況,對比分析不同工況下的冷卻時間、瞬時冷卻速率以及瞬時冷卻均勻性,從冷卻時間與冷卻所需能耗考慮給出較佳的預(yù)冷送風(fēng)速度。研究結(jié)果表明,當(dāng)送風(fēng)速度超過2.5m/s時,其制冷時間、冷卻速率及冷卻均勻性無顯著改善,通過將果品F6、S6表層、中心溫度模擬值與實驗值對比驗證得出,溫度最高偏差不大于1.5℃,其最大均方根誤差與平均相對誤差分別為1.179℃和13.6%。該研究為提高蘋果通風(fēng)包裝箱內(nèi)部預(yù)冷均勻性,選取較佳的送風(fēng)速度,降低預(yù)冷時間及減少不必要的預(yù)冷能耗提供了理論參考。

    Abstract:

    To ensure the quality and safety, and extend storage and shelf life of horticultural products across the entire coldchain, a critical step in the postharvest cold chain is rapid precooling after harvest to remove field heat. This work established a threedimensional mathematical model of airinflow and heat transfer for analyzing the aerodynamic and thermal forcedconvection cooling of vented packages simultaneously. A direct model that uses the explicit geometry of stacked products in boxes was developed earlier and was used to study the local and average airinflow through stacks of horticultural products (the package wall, trays and apples). This study is based on an existing twolayer corrugated box for precooling fresh apples. We accounted for the heat of respiration, transpiration, condensation and convective heat flow inside the produce zone. The results show that a reasonable increasing cooling rate and uniformity are obtained with an increase in airinflow velocity to 2.5m/s; any further increase in airinflow velocity simply wastes energy because it leads to a relatively low increase in cooling rate and uniformity. The model was verified by comparing its results to those of experiments. The predicted results were consistent with the measured results. The maximum temperature deviation was less than 1.5℃, and the maximum root mean square error and average relative error for produce temperature were 1.179℃ and 13.6%, respectively. This research thus provides a reliable theoretical basis for improving air-inflow and produce-temperature uniformity and minimizing energy consumption during forcedconvection cooling of produce.

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韓佳偉,趙春江,楊信廷,錢建平,邢 斌,范蓓蕾.送風(fēng)風(fēng)速對蘋果差壓預(yù)冷性能的影響[J].農(nóng)業(yè)機(jī)械學(xué)報,2015,46(11):280-289. Han Jiawei, Zhao Chunjiang, Yang Xinting, Qian Jianping, Xing Bin, Fan Beilei. Effect of Air-inflow Velocity on Cooling Efficiency during Forced-air Precooling of Apples[J]. Transactions of the Chinese Society for Agricultural Machinery,2015,46(11):280-289.

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  • 收稿日期:2015-07-09
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  • 在線發(fā)布日期: 2015-11-10
  • 出版日期: 2015-11-10