The effect of air velocity on the performance of the direct evaporative cooling system

This experimental study aimed to determine the effect of airflow velocity on the performance of a direct evaporative cooling system. Rectangular-shaped honeycomb cooling pads with a length of 34 cm, a width of 25 cm, and a thickness of 3.5 cm are used as cooling media. The main parameters of the study are low air velocity (2.3 ms−1), medium (3.2 ms−1), and high velocity (3.7 ms−1). The data collected include dry bulb temperature, wet bulb temperature, output air temperature, input and output air velocity, input and output humidity, and solar radiation. These data are used to determine saturation efficiency, cooling capacity, temperature decreases, and feasibility index. The experimental results are presented in the form of tables and graphs and analysed based on existing theories. The results showed that the evaporative cooling system could produce output temperatures up to 27.5°C with input 31.4°C at low airspeed, 27.97°C with input 31.47oC at medium speed, and 27.7°C with input 31.30°C at high air speed. It was concluded that a low airflow rate would add to the cooling efficiency, and the higher the airflow rate, the lower the cooling efficiency. The results showed that evaporative cooling is achievable with a feasibility index of 19.89 ≤ F*≤ 20.67. The results also affirmed that cooling capability is higher where the feasibility indexes are comparatively low.

Performance Assessment of Green Filtration System with Evaporative Cooling to Improve Indoor Air Quality (IAQ)

This paper focuses on the performance assessment of the green filtration system that incorporated with evaporative cooling that used to enhance indoor air quality. This system was invented in an attempt to thrive in a clean environment that becomes a solution for certain places. Indoor air quality (IAQ) and public health risk related to each other, it is due to the percentage of the city population that stays indoors rather than go outdoors. Indoor air contamination is originated from mixed origins such as volatile organic compounds (VOCs) and indoor airborne particulate matter (PM). The results show that the green filtration system manages to filter PM and VOCs in the air but not as efficient as modern air filters in the market. Furthermore, the evaporative cooling system possesses a huge deal in energy-saving within hot and arid climatic regions.

CFD MODELLING AND VALIDATION OF AMBIENT FACTORS IN EVAPORATIVE COLD STORE FOR PEACH STORAGE

Spatial variation of temperature and relative humidity were estimated with Computational Fluid Dynamics (CFD) at top, middle and base levels for peach storage at +1oC and 90% relative humidity and verified with measured data in a cold store with evaporative cooling system. Storage temperature was +1oC and relative humidity 90% for peach storage. Ansys Fluent Software was used for CFD modelling. CFD models were validated with sensors measurements. Results were evaluated by using descriptive statistics, relative error and variance analyses. Mean difference between the model and measurements was calculated as 0.51oC for ambient temperature and as 3.47 % for relative humidity. Relative error of the CFD model was calculated as 9.77 for the ambient temperature and 1.29 for relative humidity for peach storage. The developed CFD models estimated the ambient factors with an acceptable error in the evaporative cold store for peach storage.

Annual thermal performance assessment of a regenerative evaporative cooling system under different climate conditions in Mexico

A numerical heat and mass transfer model with thermophysical properties dependent on the temperature, humidity ratio and atmospheric pressure was developed. The numerical model was verified and validated against literature, and it showed good agreements. The pseudo-transient model provides a low-cost computational tool to evaluate the potential and performance of a dew point evaporative cooling system for a wide range of extreme climate conditions (BWh, BSh, Cw and Aw from Köppen classification). A parametric analysis of different operational and design conditions in the evaporative cooler was conducted. Results show that there is an optimal channel length for given climatic conditions. The Dew-point evaporative cooling (DPEC) system showed that the best thermal performance corresponds to the climate very arid (Hermosillo – BWh) with 4018 comfort hours (83.1%) followed by the climate arid (Monterrey – BSh) with 3470 comfort hours (90.9%), the mild climate (Puebla – Cw) with 295 comfort hours (100%) and the warm climate (Cancun – Aw) with 3452 comfort hours (62.3%). Finally, an engineering correlation for constant atmospheric pressure and channel length was obtained ([Formula: see text] of 93%).

STORABILITY POTENTIAL OF CARROT (Daucuscarota L.) UNDER STEM SPONGE PADDED EVAPORATIVE COOLING STRUCTURES

A zero energy stem sponge padded evaporative cooling storage was evaluated using fresh carrots (Daucuscarota L.) with control refrigerator and a similar structure without any cooling pad. The overall percentage loss in weight (during the period of experiment) of the carrot was much in the refrigerator (53.97%) and control structure (32.80%) compared to those stored in the evaporative cooling structure (25.19%). Similarly, trend of result was recorded in firmness, loss in firmnesss of the carrots stored in the control structure was greater than the ones in the evaporative cooling sytructre. However, the evaluation of the evaporative cooling system shows that the carrots can be stored for an average of twelve (12) days with negligible changes in weight, colour and firmness unlike the refrigerator and the control structure which noticeable changes began to occur from the fifth day. The modification of the microclimate by use of the zero energy evaporative and evapotranspirative cooling principles helps attain the microclimate conditions favourable for longer storage periods. With reference to the developed stem sponge padded cooler in this study, the modified environment helped in reducing respiration and metabolic rates in the stored carrots. The high relative humidity and low temperatures in the padded evaporative cooling system discouraged microorganism action on the stored carrots leading to a lengthened shelf-life