Evaporative pad cooling model validation in a closed dairy cattle building

Comparative Analysis of the Cooling Efficiency in Tropical Climate of Three Alternative Materials for Evaporative Cooling Pads

“…In this matter, Liao et al [13] proposed to scale the Hilper correlations [34] by the quotient between the characteristic length (l e ) and thickness (L) of the pad. This was validated later by [32,35,36] for pads manufactured with cellulose, showing good agreement between the experimental and numerical results. Moreover, few authors have reported the convective heat and mass transfer coefficients or the characteristic length [7,13,21,26,30,33], making it difficult to develop future simulations of the same material under different conditions.…”

“…The thickness was selected from a balance between pressure drop and cooling efficiency from previous research [28]. The pads were tested in an instrumented wind tunnel [32], increasing the air inlet velocity (u) from 0.5 m s −1 to 3.5 m s −1 for the cellulose pad or with the pressure below 160 Pa or until test failure due to water force out of the pad. In addition, three water flows (Q) around the recommended value of 6.2 L min −1 m −1 [46] were tested: 2, 6.2 and 10 L min −1 m −1 , to determine their incidence over the pressure drop across the pad.…”

“…In addition, three water flows (Q) around the recommended value of 6.2 L min −1 m −1 [46] were tested: 2, 6.2 and 10 L min −1 m −1 , to determine their incidence over the pressure drop across the pad. The mathematical model that described the fluid-dynamic and hygrothermal behaviour of cooling pads, proposed by Obando et al [32], was used in order to compare the behaviour of the pads at different inlet air velocities (u: 0.5 to 2 m −1 ), thickness of pad (L: 0.05 to 0.15 m) and environmental conditions: dry-bulb temperature (T db i : 25 to 35 • C) and relative humidity (φ i : 30 to 70%) of the inlet air. Twenty-one equidistant values from the inlet air relative humidity (φ i ) interval and 11 values for each one of the other variables were selected, obtaining 307,461 combinations of different conditions to simulate for each pad.…”

“…However, conducting experimental tests to assess the influence of all factors on cooling efficiency is a time and resource consuming task. Some phenomenology mathematical models had been proposed and validated through experimental tests [32,33] to address this issue, determining the behaviour of the pad under different environmental, operating and manufacturing conditions. This has been done exhaustively for cellulose pads, nevertheless, the main difficulty that arose for alternative materials is the computation of their convective heat and mass transfer coefficients, in addition to the computation of the air-water contact surface area.…”

Experiments on Energy-Efficient Evaporative Cooling Systems for Poultry Farm Application in Multan (Pakistan)

“…Energy consumption is also lower in EC systems as compared to the VCAC [38]. When ambient air is passed through any water steam directly or indirectly, it gets cooled with the effect of water evaporation into the air [20,31,39]. EC system is generally employed in hot and relatively dry climates [7].…”