Guo Liangjie, Chen Xinyi, Yang Shiye, Zhou Ruimin, Liu Shenyan, Cao Yanfei
College of Horticulture, Northwest A & F University, Yangling 712100, China.
Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Yangling 712100, China.
Plants (Basel). 2024 Mar 4;13(5):718. doi: 10.3390/plants13050718.
In cold regions, the low irrigation water temperature is an important factor of low-temperature stress for greenhouse crops. In this paper, an irrigation water-heating system (IWHS) is proposed to increase the water temperature by utilizing the excess heat in the solar greenhouse. The heat-collection capacity of the system was analyzed by screening the IWHS process parameters in a Chinese solar greenhouse, and a warm-water irrigation experiment for lettuce was conducted. The results demonstrated that the water temperature increased with the increase in wind speed, and the increase in daily average water temperature reached the maximum value of 8.6 °C at 4.5 m/s wind speed. When the heat exchanger was installed at a height of 3.0 m, the collector capacity increased by 17.8% and 6.0% compared with the heating capacity at 0 m and 1.5 m, respectively, and the operation termination water temperature was 22.0-32.2 °C and its coefficient of performance (COP) was optimal. Surface darkening of the heat exchanger did not affect the heat-collection capacity of the system. Using the IWHS effectively improved the temperature of lettuce irrigation water in the Chinese solar greenhouse. The increased frequency of warm-water irrigation significantly promoted lettuce growth and increased the average yield per plant by 15.9%. Therefore, IWHS effectively increased the irrigation water temperature in a Chinese solar greenhouse in winter. Improving the system would enhance its economic and application value.
在寒冷地区，灌溉水温较低是温室作物遭受低温胁迫的一个重要因素。本文提出了一种灌溉水加热系统（IWHS），利用日光温室内的余热来提高水温。通过筛选中国日光温室中IWHS的工艺参数，分析了该系统的集热能力，并进行了生菜温水灌溉试验。结果表明，水温随风速增加而升高，在风速为4.5 m/s时，日平均水温升高最大值达到8.6℃。当热交换器安装高度为3.0 m时，与安装高度为0 m和1.5 m时的加热能力相比，集热能力分别提高了17.8%和6.0%，运行终止水温为22.0 - 32.2℃，其性能系数（COP）最佳。热交换器表面变黑不影响系统的集热能力。使用IWHS有效地提高了中国日光温室中生菜灌溉水的温度。增加温水灌溉频率显著促进了生菜生长，单株平均产量提高了15.9%。因此，IWHS有效地提高了中国日光温室冬季的灌溉水温。对该系统进行改进将提高其经济价值和应用价值。
