内置潜热储能的阶梯式太阳能蒸馏器的瞬态性能

Abdulhaiy M. Radhwan

海水淡化171 (2004)61-76

摘要

研究了带潜热储能的阶梯式太阳能蒸馏器的瞬态性能。该蒸馏器用于偏远地区农业大棚(GH)的加热和加湿。太阳能蒸馏器由五个带有倾斜玻璃罩的阶梯式盆组成，底部是绝缘的。该盆被放置在一个充满石蜡层(相变材料，PCM)的平板上，作为潜热热能存储系统(LHTESS)。来自GH的空气从底部进入蒸馏器，在被加热和加湿的盆地和玻璃罩之间流动，然后回流到GH。对所研究的蒸馏器性能参数进行了分析，并与没有lhess的蒸馏器进行了比较。结果表明，采用LHTESS的蒸馏器效率为57%，日总产量约为4.6 L/m2。静止温度、出风温度和GH热负荷的正弦趋势比无LHTESS的静止温度、出口温度和GH热负荷的正弦趋势更为均匀。结果表明，在饱和条件下，循环空气相对湿度沿静压区逐渐增大，始终保持不变。结果表明，减小空气流量对蒸馏收率影响不显著，而GH热负荷降低。 For a selected design and operational parameters, the still was able to provide heat for the GH for 24 h/d. This finding is important since heat could be provided to the GH at night and when it is most needed.

作者

Abdulhaiy M. Radhwan（2）

结论

1.研究了一种用于农业大棚加热加湿的阶梯式太阳能蒸馏器的瞬态热性能。蒸馏器有一个简单的设计，吸收器由五个阶梯式(黑色涂层和绝缘)小盆组成，盛着停滞的盐水。盆被放置在装有石蜡的板状容器上，用于储存热能。空气(来自温室)在热水和倾斜的玻璃罩(加热和加湿的地方)之间循环，然后流回温室。2.研究了蒸馏器的性能参数，包括组件温度、温室热率、出口空气温度和湿度以及产量和效率。结果表明:C型蒸馏器的效率为57%，而没有LHTESS的蒸馏器的效率为61%。C总的日产量约为4.6 L/m2，而没有LHTESS的仍为4.9 L/m2。C与没有LHTESS的蒸馏器的正弦趋势相比，蒸馏器的温度更加均匀。 C The relative humidity of the circulating air increased along the still and always leaves at saturation conditions. C A decreasing air flow rate has insignificant influence on the system productivity; however, it influences the greenhouse heat load. C When using a selected combination of parameters (the absorber is placed on a 5-cm thickness of paraffin wax with a 50°C melting temperature, covering the glass after sunset), A C G h Hfg H — — — — — — I k L l M m p Pr Q s t T Th v w — — — — — — — — — — — — — — — Area, m2 Specific heat, J/kg °C Grashoff number Specific enthalpy, J/kg Latent heat of evaporation, J/kg Film coefficient of heat transfer, W/m2 °C Solar intensity, W/m2 Thermal conductivity, W/m.°C Length, m Liquid Mass, kg Mass rate, kg/s Pressure, Pa Prandtl number Heat transfer rate, W Solid Time, s Temperature, °C Thickness, m Velocity, m/s Humidity ratio, kgwater /kgair — — — — — — — — — — Absorbtivity Incremental rise Difference Emissivity Relative humidity Efficiency Reflectivity Radiation constant Summation Transmisivity Greek " * ) g N D F E J Subscripts a ab am av b C COND E eq Eff g gh h i inst K m o p pw R s sid s/l su sw w — — — — — — — — — — — — — — — — — — — — — — — — — — — — — Circulating air Absorber Ambient Average Base Convection Condensation Evaporation Equivalent Effective Glass Greenhouse Humidification Insulation Instantaneous Conduction Melting Outlet Projected Product water Radiation Sky Side (glass cover) Solid/liquid Sun Saline water Wind Inlet Outlet

来源:http://www.desline.com/articoli/5926.pdf

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