Set up a test-bed, test the pre-cooling section, cooling section, and the units consist of them separately, then analysis the data. Within the experimental range, the best ratio of the secondary air volume and the primary air volume is 1.2 for the pre-cooling section, for the cooling section is 1.69. The outlet air temperature is below its wet bulb temperature for the units, and higher than its dew point temperature.
Abstract
Maintaining good production quality in layer poultry houses is directly correlated to the thermal environment of the laying hens as well as their breathable air quality. This work compares the performance of two passive cooling systems in meeting the thermal and indoor air quality requirements (CO2, water vapor and NH3) in a layer house in Doha, Qatar characterized by a semi-arid climate. The first system is a standalone cross flow dew point evaporative cooler (DPIEC) supplying air through a localized air distribution system. The second system is a DPIEC aided by a radiative cooling (RC) panel that pre-cools the supply fresh air, in an effort to reduce the system sizing, air and water consumption even further. To achieve these objectives, a modular analysis was adopted, where mathematical models were developed for the DPIEC and RC systems and the poultry house module conditioned by the localized system. A 3D CFD model was developed for the compartment conditioned by the localized system. The DPIEC was sized and the hourly variation in needed supply fresh air and water was determined for the critical month of May, June July of the summer season.
Refreshing air remains a crucial problem in warm climates where electricity consumption for air conditioning has become excessive and irrational for several years, notably in Algeria. Research in this field is increasingly oriented towards new techniques that can reduce costs and environmental impacts. Among these techniques, the evaporative dew point cooling technology is the most promising as it can cool outdoor air to temperatures below its wet bulb temperature. The aim of this work is to model and design a dew point cooler for french and algerian climates. This model is used to study the effect of the cooler parameters such as its length, water temperature and working air ratio on its cooling effectiveness and supply temperature.
Abstract
In this paper, the effects of regenerative evaporative coolers on the dry desiccant air cooling system are assessed. Thermodynamic analysis is performed point by point on the unmodified (ɛ = 0.67) and modified (ɛ = 1) regenerative evaporative cooler supported systems. It is found that the effectiveness and efficiency of the system were significantly increased by modification. Effectiveness of the system increases from 0.95 to 2.16 for the wet bulb and from 0.63 to 1.43 for dew point effectivenesses, while the exergy efficiency increases from 18.40% to 41.93%. Exergy and energy performances of the system increase 1.28 times and 0.61 times, respectively. Finally, sustainability is increased by 40% with the modification of the regenerative evaporative cooler. Also, changing the regenerative evaporative cooler of the solid desiccant wheel with the effective one can increase the overall system efficiency and performance without changing the sensible heat and desiccant wheels.
This study investigated the annual energy saving potential and system performance of two different evaporative cooling-based liquid desiccant and evaporative cooling-assisted air conditioning systems. One system used an indirect and direct evaporative cooler with a two-stage package to match the target supply air point. The other was equipped with a single-stage, packaged dew-point evaporative cooler that used a portion of the process air, which had been dehumidified in advance. Systems installed with the two evaporative coolers were compared to determine which one was more energy efficient and which one could provide better thermal comfort for building occupants in a given climate zone, using detailed simulation data. The detailed energy consumption data of these two systems were estimated using an engineering equation solver with each component model. The results showed that the liquid desiccant and dew-point evaporative-cooler-assisted 100% outdoor air system (LDEOAS) resulted in approximately 34% more annual primary energy consumption than that of the liquid desiccant and the indirect and direct evaporative-cooler-assisted 100% outdoor air system (LDIDECOAS). However, the LDEOAS could provide drier and cooler supply air, compared with the LDIDECOAS. In conclusion, LDIDECOAS has a higher energy saving potential than LDEOAS, with an acceptable level of thermal comfort.
Two-dimensional numerical study of a heat and mass exchanger for a dew-point evaporative cooler
