Abstract:
Currently, there is a trend of using greenhouses in agriculture combined with
evaporative cooling systems to control factors suitable for crop cultivation and animal
husbandry. Typically, cooling pads made of paper are used, which have limitations in
terms of lifespan and high costs. Therefore, this research aims to compare the
efficiency of cooling pads made of paper with biochars for evaporative cooling systems.
The biochar consists of three types: 1) rice husk biochar, 2) eucalyptus biochar, and
3) bamboo biochar, each sized 20 cm wide, 20 cm high, and 6 cm thick. Experiments
are conducted in two sizes of testing boxes (size 1: 20 cm wide x 20 cm high x 85 cm
long, and size 2: double the size of size 1).
The study found that eucalyptus biochar can achieve the highest average
temperature reduction of 7.06 oC and can maintain relative humidity at a constant of
73.80%, which is close to the performance of paper (82.11%). The evaporative cooling
efficiency, it was found that eucalyptus biochar and bamboo biochar have similar
efficiency to paper in size 1 (64.25, 65.70 and 63.71%, respectively). However, when the
size is doubled, the efficiency of bamboo biochar decreases, while eucalyptus biochar
remains constant, and paper efficiency increases.Statistically significant (p≤0.05)
Regarding the cost-effectiveness analysis of the cooling process, it was found that
eucalyptus biochar has the lowest average cost (2.7 baht/m2), while the cooling pads
made of paper have significantly increased cost-effectiveness as the size increases.
Therefore, this study suggests that eucalyptus biochar is a suitable option for producing
cooling pads in evaporative cooling systems due to its high water absorption capacity,
significant porosity, long lifespan, and ability to prevent fungal growth, benefiting both
plants, animals, and workers in the greenhouse. Additionally, it addresses long-termenvironmental issues by promoting biodegradation and helping reduce agricultural and
community waste.