土壤水分周年变化有明显的阶段性，有利于小麦生长，旱塬小麦耗水系数高，水分利用效率低。
The yearly variation of soil and water is obviously characterized by stages, which is favourable for wheat growth.
通过实验方法测试了以原生长江水为冷却水的换热器污垢热阻和摩阻系数的变化。
The variation of fouling resistance and frictional resistance coefficient of heat exchanger using connate Yangtze River water as cooling water is tested experimentally.
进一步研究了在结霜过程中空气冷却器的传热面积、传热系数以及空气侧压降与霜层生长的变化关系。
Through expounding the calculation process of the external wall, roofing, floor and door and window heat transmission coefficient, the article investigates the energy-savingc alculation.
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