Performance Assessment of a Solar-Assisted Desiccant-Based Air Handling Unit Considering Different Scenarios

Abstract

Abstract:In this paper, three alternative layouts (scenarios) of an innovative solar-assisted hybrid desiccant-based air handling unit (AHU) are investigated through dynamic simulations. Performance is evaluated with respect to a reference system and compared to those of the innovative plant without modifications. For each scenario, different collector types, surfaces and tilt angles are considered. The effect of the solar thermal energy surplus exploitation for other low-temperature uses is also investigated. The first alternative scenario consists of the recovery of the heat rejected by the condenser of the chiller to pre-heat the regeneration air. The second scenario considers the pre-heating of regeneration air with the warmer regeneration air exiting the desiccant wheel (DW). The last scenario provides pre-cooling of the process air before entering the DW. Results reveal that the plants with evacuated solar collectors (SC) can ensure primary energy savings (15%-24%) and avoid equivalent CO 2 emissions (14%-22%), about 10 percentage points more than those with flat-plate collectors, when the solar thermal energy is used only for air conditioning and the collectors have the best tilt angle. If all of the solar thermal energy is considered, the best results with evacuated tube collectors are approximately 73% in terms of primary energy saving, 71% in terms of avoided equivalent CO 2 emissions and a payback period of six years.

Comparison of Different Solar-Assisted Air Conditioning Systems for Australian Office Buildings

“…Khan et al [47] found out that based on various collector areas, for Chennai city, the solar desiccant-assisted Dedicated Outdoor Air System (DOAS) integrated radiant cooling system could achieve 7.4% to 28.6% energy savings in comparison with the cooling coil-assisted DOAS radiant cooling system. In the last several decades, solar-assisted cooling technology has widely been evaluated worldwide, including solar electric cooling powered by PV [15][16][17], solar absorption cooling [18][19][20][21][22][23], solar adsorption cooling [24,25], and solar desiccant cooling [26][27][28][29][30][31][32][33][34][35]. A theoretical modelling with experimental validation studied by Nie et al [36] demonstrated that the solid desiccant cooling assisted by heat pump was more efficient than the conventional cooling system due to high efficient dehumidification capacity.…”

Effect of Evaporator Position on Heat Pump Assisted Solid Desiccant Cooling Systems

“…Ghulam Qadar Chaudhary et al found that solar energy contributes 70% of the regenerative heat in the system [17]. Other scholars have proved the high utilization rate of solar thermal energy through solar fraction [18], which can also reach 0.67 in March [19]. However, with regard to solar energy, there is no sufficient regeneration heat to ensure the effective operation of the desiccant wheel in days of high humidity and low solar radiation [20].…”

Experimental energy performance assessment of a solar desiccant cooling system in Southern Europe climates

“…Therefore, an efficient cooling system to reduce the high air temperatures generated in the dehumidification process and control the supply air temperature, would allow the sensible and latent heat to be decoupled. Numerous hybrid HVAC systems have been analysed by some authors in the available literature [11][12][13][14]. A DW integrated with a vapour compression system was analysed, where the evaporator was used to cool the process air and the condenser to thermally activate the DW [15,16], but these systems almost always depend on electrical energy.…”