Evaporation characteristics of a solar irradiated naturally ventilated class a pan
Evaporative water loss is of significant importance in many fields ranging from hydrology and agriculture, to food science and engineering applications. Water removal from industrial effluent streams, food processing industry and the biodiesel conversion process from microalgae is an important st...
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| Format: | Thesis |
| Language: | English |
| Published: |
2016
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| Subjects: | |
| Online Access: | https://eprints.ums.edu.my/id/eprint/17835/1/Evaporation%20characteristics.pdf https://eprints.ums.edu.my/id/eprint/17835/ |
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| Summary: | Evaporative water loss is of significant importance in many fields ranging from
hydrology and agriculture, to food science and engineering applications. Water
removal from industrial effluent streams, food processing industry and the biodiesel
conversion process from microalgae is an important step in wastewater and sludge
treatment, harvesting and drying of crops. The purpose of the experiment was to
observe the characteristics of evaporation from class A pan and to enhance the rate
of evaporation flux by using enhanced natural draft that showed Chu et al. in
(2012) by installing wire mesh on the chimney to impede cold inflow. This study
monitors the effect of natural draft flow enhancement on evaporation. Experiments
were conducted in square shape pan at three different. sizes. Dimensions of the
experimental pans were side lengths 1.07m, 0.6m and 0.6m; depth 0.254m,
0.254m and 0.2m respectively. The solid wall type solar irradiated chimney was
used to enhance natural draft in this research. There were two designs of solar
irradiated naturally ventilated pan (SINVAP). The specification for Design-1 category
SINVAP was 0.105m2,0.28m2 and 0.77m for inlet opening area, outlet opening
area and solid wall chimney height respectively. The dimensions 8.65x10-3 m2,
0.26m2 and 1.2m were the corresponding values of Design-2 type SINVAP. A
0.64mmxO6. 4mm size wire mesh was installed at the outlet of the SINVAP to
impede cold inflow in the SINVAP. Over about 100 days evaporation readings were
taken using the different pan configurations. The experimental result showed the
evaporation flux from the SINVAP with wire mesh at outlet opening was around
14% more than the open pan; in the SINVAP without wire mesh at outlet opening
was lower than the open pan evaporation rate. The SINVAP evaporation flux was
found to be moderately influenced by the net radiation, vapor pressure deficit and
natural ventilation draft. The daily average net radiation in the SINVAP water was
reduced due to reflection of incoming global radiation at the transparent plastic
sheet. Reduction of net radiation in the SINVAP could have caused evaporation to
be lower than open pan. The vapor pressure deficit followed the opposite trend of
net radiation; as a result, the evaporation flux from the SINVAP with wire mesh has
been increased. The elevated vapor deficit in the SINVAP with wire mesh could
have caused evaporation to be higher than the open pan. This research found the
average local wind run over the open pan was higher than the SINVAP inlet air
flow. The nature of the local wind flow profile was unsteady and always fluctuated.
However, the inlet air flow profile in the SINVAP was smooth, with little fluctuation.
The smooth inlet air flow in the SINVAP was instrumental in transferring higher
amount of water vapor molecules from the pan into the air. According to the
findings of this study, the use of Chu et al., (2012) enhanced natural draft in the
application fields of pond natural evaporation seems promising. The dimensions if
chosen properly can thus substantially increase evaporation rates. |
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