直膨式太阳能热泵用于温室番茄根际-空气加温的试验研究

Experimental study on the rhizosphere-air heating with direct-expansion solar-assisted heat pump of tomato in greenhouse

关键词:  大跨度温室  直膨式太阳能热泵  温室加温  性能系数  运行模式  根际加温

Key words:  large-span greenhouse  direct-expansion solar-assisted heat pump  greenhouse heating  coefficient of performance  energy conservation  operational mode  rhizosphere heating

摘要:

针对直膨式太阳能热泵所集热能利用率低，温室加温不足的问题，采用直膨式太阳能热泵为集热系统，根际-空气加温为放热系统，对大跨度主动蓄能型温室在不同天气仅根际加温和根际与空气同时加温的加温效果，集、放热系统运行性能，集热效率，热能利用率，节能率和集热系统的优化运行模式进行研究。结果表明：1）连续阴天和连续晴天，放热系统的热能利用率分别高于97.2%和92.7%；2）不同天气试验区的根际温度在17.9℃以上，比对照区高1.5℃，空气温度在11.6℃以上，比对照区高3.6℃，相对湿度在90.8%以下，比对照区低3.2%；3）不同天气整套系统的节能率R在47.2%以上，性能系数在1.9以上；4）不同天气集热系统均能在设定时间内达到设定集热温度目标，且其集热性能系数COP_c在2.3以上，其集热效率在149.6%以上；5）9：30-11：30集热系统COP_c随太阳辐射强度的增大，从1.4增大至3.0，11：30-14：50集热系统的集热性能系数均高于3.8，15：10以后，蓄热水池水温高于47℃时，集热性能系数由3.2最终降至0.8。该研究表明根际与空气结合的加温方式不仅提高了温室加温效果，还提高了热能利用率和直膨式太阳能热泵的集热性能。此外，根据集热条件调节集热系统的运行模式，可提高集热性能，达到温室加温节能的目的。

Abstract:

In order to increase the heat energy utilization efficiency of direct-expansion solar-assisted heat pump (DX-SAHP),a mechanism was designed by using DX-SAHP as collection system and rhizosphere-air heating as releasing system. The heating effect,coefficient of performance (COP) and heat-collecting efficiency were tested.The operation mode under different weather conditions was optimized.The results showed that:Under the conditions of consecutive cloudy days and consecutive sunny days,the heat utilization efficiency of the heat releasing system was higher than 97.2% and 92.7% correspondly;Under different weather conditions,the rhizosphere temperature and air temperature in the experimental area were above 17.9 and 11.6 ℃ respectively,which were 1.5 and 3.6 ℃ higher than those of the control area;The relative humidity in the experimental area was below 90.8%,which was 3.2% lower than that of the control area;The energy-saving rate R of the whole system under different weather conditions was higher than 47.2%,and the coefficient of performance (COP_total) was above 1.9;Under different weather conditions,the heat collecting system could reach the set temperature objective for heating within the set time while keep the coefficient of heat-collecting performance (COP_c) above 2.3 and the heat-collecting efficiency μ higher than 149.6%;Additionally,from 9:30 am to 11:30 am,with the increase in solar radiation intensity,the COP_c of the heat collecting system also increased from 1.4 to 3.0;from 11:30 am to 14:50,the COP_c of the heat-collecting system was above 3.8;After 15:10 when the temperature of water in the thermal storage tank was higher than 47 ℃,the COP_c finally dropped from 3.2 to 0.8.In conclusion,this study clarified that the DX-SAHP heating rhizosphere-air could not only improve the heating effect of greenhouse,but also improve the heat energy utilization rate and the COP_c of the DX-SAHP.Additionally,it could realize the greenhouse energy conservation goal by using the operating mode of DX-SAHP,which could be adjusted in accordance with variations in solar radiation intensity and the water temperature in the tank.