2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 155 -
Abstract
--This research presents a study of the
performances of pork drying by using a greenhouse dryer.
The dryer has a semi-cylindrical roof and is covered with
polycarbonate sheets. The base of the dryer is a concrete
floor with the area of 12.6 m
2
. Four DC axial flow fans
powered by a 30 W PV module are used to ventilate the
dryer. The dryer was installed at Kalasin (16
q
25
c
N,
103
q
30
c
E) in Thailand. To investigate its performance, the
dryer was used to dry pork. During the experiments, the
pork was dried to the final moisture content of 70% db from
210% db in 280 min and it took 340 min in open sun drying,
the drying time was reduced by about 21.4%. The
maximum and daily drying efficiencies of the greenhouse
dryer were 65.4% and 44.8%, respectively. Due to its
simplicity, the proposed system is relatively inexpensive.
Therefore, commercial application seems to be viable.
Index Terms
--Drying Efficiency, Drying Time, Moisture
Content, Solar Drying,
I. I
NTRODUCTION
Thailand is one of the countries well known for its
livestock products; pork being one of them. The Office
of Agricultural Economics of Thailand reported that pork
products alone totaled 0.97 tons in 2010. Added value is
available to fresh pork in the form of dried pork. The
drying of pork can be accomplished using several
different methods, i.e., open sun drying, cabinet drying,
and greenhouse drying. The greenhouse dryer seems to be
the best choice because it provides a controlled
environment in terms of moderate temperature and
humidity which is beneficial to the pork being dried more
effectively thus reducing the drying time. Drying can also
be accomplished with a solar cabinet dryer, but the high
temperature is not desirable. Another consideration is
cost; it is economically efficient to dry the same volume
of pork inside the greenhouse as inside the cabinet dryer.
Solar energy is one of the most promising renewable
energy sources in the world, especially in Thailand.
Thailand is located in the tropical region of the Southeast
Asia and receives an annual average daily solar radiation
of 18.2 MJ/m
2
[1]. Solar drying is a continuous process
where moisture content, air and product temperature
change simultaneously along with the two basic inputs to
the system, i.e., solar radiation and ambient temperature.
The drying rate is affected by ambient climate conditions.
This includes temperature, relative humidity, sunshine
hours, available solar intensity, wind velocity frequency
and duration of rain showers during the drying period.
This work was supported by Thailand Research Funds (TRF).
The greenhouse dryer is a system that uses the
standard greenhouse structure to work as a solar dryer
during the warmer months of the year. A greenhouse is
essentially an enclosed structure, which traps short
wavelength solar radiation and stores long wavelength
thermal radiation to create a favorable micro-climate for
higher productivity. The product is placed in trays
receiving solar radiation through the cover, while
moisture is removed by natural convection or forced air
flow. Many advantages of a greenhouse dryer are simple
structure, large load capacity and relative good thermal
performance [2]. Various investigators have studied the
greenhouse for drying agricultural products such as
Condori et al. [3] whom studied a tunnel greenhouse for
drying sweet pepper and garlic. Kumar and Tiwari [4]
developed a thermal modeling of jiggery drying in a
natural convection solar greenhouse dryer. A PV-
ventilated greenhouse dryer for drying 100-150 kg of
chilies was designed and tested by Janjai et al. [5]. The
same greenhouse was also used for drying peeled longan
and banana [6]. A mathematical modeling based on
energy and mass balance was developed for predict the
air and moisture contents of peeled longan and banana
during drying. The simulation results reasonably agreed
with the experimental data. Kumar and Tiwari [7]
compared the convective mass transfer coefficient of
open sun drying, greenhouse dryer under natural and
forced convections for drying onion flakes. It was found
that the rate of moisture evaporation in case of
greenhouse drying is more than that in open sun drying
during the off sunshine hours due to the stored energy
inside the greenhouse. Jain [8] presented a transient
analytical model to study the application of a greenhouse
with packed bed storage to crop drying. In all of the
literature reviews above the greenhouse dryers were used
to dry many crops. None of these works studied the
drying of meat, such as pork, using the greenhouse dryer.
The objective of this study was to investigate the
performance of the greenhouse dryer under prevailing
climatic conditions of Thailand.
II. M
ATERIAL AND
M
ETHOD
A. Greenhouse Dryer
The schematic diagram of the roof type semi-
cylindrical greenhouse dryer is shown in Fig. 1. It
consists of a semi-cylindrical roof structure made of
polycarbonate sheets on a concrete floor. The
polycarbonate sheets have many advantages over other
Experimental Performance of a Greenhouse
Dryer for Pork Drying
M. Boonyasri, C. Lertsatitthanakorn, L. Wiset and N. Poomsa-ad
Faculty of Engineering, Khantarawichai, Mahasarakham University, (
Thailand
)
, (
Thailand
)
