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Three typical commercial buildings in Chongqing, P.R. China were selected to study the actual summertime operation and energy situations of heating ventilating and air conditioning (HVAC) systems in commercial buildings. Based on tests of energy consumption of HVAC systems in these three buildings, we analyzed the electricity consumption of the main components of the air conditioning systems. The energy efficiency of the chillers and air conditioning water distribution systems were studied. The indoor thermal environment in these three buildings were also tested and discussed. It is concluded that problems exist in the air conditioning systems of commercial buildings. Among the problems are over sized system design, low equipment operating efficiencies, poor operation management, and lack of indoor temperature controls. To reduce energy consumption of HVAC systems in commercial buildings, we propose energy efficient strategies such as sizing systems based on accurate load calculation and automatic control under partial load conditions. 相似文献
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苹果切片红外辐射干燥模型建立与评价 总被引:1,自引:0,他引:1
选择加热温度为60℃,辐射功率为750W,辐射距离为100mm,物料厚度为5mm时的红外辐射干燥苹果切片试验数据作为实测值样本,基于Matlab软件,利用高斯-牛顿算法,对传统干燥模型进行非线性最小二乘数据拟合求解,确定干燥系数。通过决定系数R2、误差平方和(SSE)及均方误差的根(RMSE)等拟合优度评价指标对各种干燥模型进行评价。结果表明,用Modified Page equationⅡ模型能够更好地预测和控制苹果切片红外辐射干燥过程。 相似文献
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采用VOF两相流模型研究了气液叉流条件下受热液膜热质传递特性,在模型中添加了表面张力源项和气液相间传质源项.为了验证所建立模型的可靠性,采用非接触式红外热成像测温方法,进行了相应的气液叉流试验.对叉流条件下受热液膜热质传递过程进行了试验和模拟计算,结果显示无量纲壁面温度计算结果与试验结果吻合很好.应用所建立的模型,模拟计算并分析了表面张力、固液接触角、液膜流量等因素对液膜流动侧形和热质传递性能的影响,结果表明:在其他参数保持不变的情况下,表面张力从0.014 N/m增大到0.072 N/m的过程中,液膜覆盖面积由82.7%减小到73.2%;固液接触角从30°增大到60°的过程中,液膜覆盖面积由80.6%减小到69.4%;液膜流量越小,液膜厚度越小,越有利于液膜的蒸发;相反,较高的液膜流量会使液膜厚度增大,阻碍了液膜蒸发,从而使外掠过液膜的单位体积空气含湿量减小. 相似文献
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In order to study the effects of different catalytic walls on combustion characteristics, the premixed catalytic combustion characteristics of methane/air in micro combustor are studied. It lays the foundation for the combustion technology of hydrocarbon fuel in micro engine. Numerical simulation of flow and catalytic combustion in micro combustor was done by using laminar finite rate and second order upwind discretization methods. The results show that when wall temperature,CH4/O2 mole ratio and methane mass flow rate change, the influence of lower catalytic wall on the methane catalytic combustion efficiency is biggest, followed by side catalytic wall, the smallest is upper catalytic wall. The methane catalytic combustion efficiency unit area of lower catalytic wall is about three times of that of upper catalytic wall. The utilization of catalyst on lower catalytic wall is maximal . Therefore, when coating catalyst, the quantity of katalyst on lower catalytic wall should be appropriate more, moderate on the side catalytic wall, as little as possible on the upper catalytic wall. The influence disciplinarian and contribution rate of different catalytic wall on methane combustion have been gained. The optimized strategy of catalyst coating was put forward and reduced the cost of catalytic combustion. 相似文献
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本研究从江苏与山东两省农村经济的总体发展和结构入手,比较了两省农村经济发展的历史,剖析了区位与交通、自然资源条件、农村劳动力、农业产业化、农业竞争力、外向型农业经济、经济改革措施等影响两省农村经济发展的主要因素,探讨了江苏与山东两省农业和农村经济发展的轨迹、经验和方略,在此基础上有针对性地提出了进一步做大做强两省农村经济的意见和建议. 相似文献