• Solar Energy
• /
• v.7 no.1
• /
• pp.14-22
• /
• 1987

This paper presents an experimental study of a solar drying system designed and installed by KIER. Experiments have been performed using the KIER system for the drying of marine products, such as squid. Presented in detail are the experimental observations of collector air temperature, solar intensity, absorber plate temperature, drying chamber temperature, humidity and other measures of drying chamber performance with variation of air mass flow rate. As a result, average temperature attained in the drying chamber during autumn weather has been adequated for drying of squids.

• Proceedings of the Korean Fiber Society Conference
• /
• 1996.10a
• /
• pp.29-34
• /
• 1996

In the present paper, the flow distribution in the hot air drying chamber of a sizing machine was numerically analyzed with respect to the geometries of the intake duct to obtain the more uniform flow distribution in the chamber. The result shows that the velocity distribution in the inlet of the chamber was significantly dependent on the the geometry of the intake duct. The degree of the non-uniformity in the chamber was reduced as the incident angle of the intake duct became to be smaller.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.8
• /
• pp.1595-1602
• /
• 1992

An energy efficient drying system, utilizing a heat pump to recover the wasted heat with high efficiency is proposed. In conventional drying systems, over-heating occurs through a condenser as the same amount of air is provided into the evaportator and the condenser. In order to prevent the over-heating, part of the outlet air from the drying chamber must be bypassed to increase the rate of vaporization in the drying chamber without release of the heat from the system. Since a part of the heat in the condenser is used to heat the air during the drying process of the proposed system, a high drying efficiency and low SPC(Specific Power Consumption) could be obtained, Comparing the performances between the proposed heat pump and a conventional one, it was found that the drying efficiency of the proposed heat pump is higher than that of the conventional heat pump by an amount of 7-25%.

• Journal of the Korean Society of Industry Convergence
• /
• v.6 no.2
• /
• pp.103-108
• /
• 2003

This study was performed to find out drying characteristics and develop waste heat recovery dryer. this system was initiated in order to recover discharged waste heat of drying air from drying chamber in agricultural products dryer and recycle for additional heat source that could save drying cost. The system consists of drying chamber, fan, burner, circulation pump and heat exchanger made of fins and tubes. For the system performance, drying experiments with fresh pepper were conducted, and comparisons on fuel consumption amount and drying performance were made between conventional dryer and the heat recovery system attached dryer.

• Korean Journal of Food Science and Technology
• /
• v.34 no.5
• /
• pp.799-804
• /
• 2002

Optimum conditions of freeze-dried carrots were determined using response surface methodology. Physicochemical and sensory properties of freeze-dried carrot prepared at different plate temperatures and chamber pressures were evaluated. Drying time increased with decreasing plate temperature and chamber pressure. Rehydration ratio decreased inversely with chamber pressure at low plate temperature, but increased proportionally with chamber pressure at high temperature. Density, color, and sensory off-flavor were not affected by the plate temperature and chamber pressure. Sensory color, tenderness, and carrot flavor increased with decreasing plate temperature, but were not affected by chamber pressure. Based on the drying time, rehydration ratio, and sensory attributes, optimum plate temperature and chamber pressure for the preparation of freeze-dried carrot were determined as $43^{\circ}C$ and 700 micronHg, respectively.

• Journal of the Korea Institute of Building Construction
• /
• v.4 no.4
• /
• pp.71-77
• /
• 2004

Drying Shrinkage has much complexity as it has relations with both internal elements of concrete and external factors. Therefore, experiments on Concrete Drying Shrinkage are carried out in this study under simplified circumstances applying temperature & Humidity test chamber which enables constant temperature and humidity. Comparative analyses have been made respectively according to the consequences aiming at modelling for prediction of Concrete Drying Shrinkage and making out measures to reduce it. Strain Rate of Drying Shrinkage of concrete under the condition of dry air appears to rise by about 20%-30% in proportion as the temperature rises $5^{\circ}C$ when the humidity was held below 10% compared under the condition of dry temperature & Humidity test chamber. Strain Rate of Drying Shrinkage in pit sand concrete increased 20% higher than measured when in river sand under the condition of 90-day material age. A general formula with two variables is derived as follow ${\varepsilon}={\alpha}_1＋{\beta}_1x_1＋{\beta}_2x_2＋{\beta}_3x_1^2＋{\beta}_5x_2^2$. and also graphed in 3 dimensions, enabling to apply to actual design and predict Strain Rate of Drying Shrinkage in concrete. The results of prediction of Rate of Drying Shrinkage by Response Surface Analysis are as follows. The coefficient of correlation of Drying Shrinkage in Concrete was over 90%.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.11 no.4
• /
• pp.1-6
• /
• 2015

In this study, energy performance of two types of food dryers which are electric heater and heat pump is studied experimentally. With drying chamber temperatures controlled at 45, 50 and $55^{\circ}C$, sliced radish is dried from an initial mass of 90 to final 7 kg. Moisture content, drying time, total power consumption, MER (moisture extraction rate, kg/h) and SMER (specific moisture extraction rate, kg/kWh) are measured and analyzed. As the drying chamber temperature is increased, drying time is shortened but energy efficiency is reduced for both types. For an electric heater dryer, the effect of chamber temperature on drying time is significant but less significant on energy efficiency. For a heat pump dryer, the dependence of chamber temperature on drying time is weak but strong on energy efficiency. Temperature levels have little effect on electric heater dryer performance but strong effect on heat pump dryer which operates on a vapor compression refrigeration cycle. The energy performance of the heat pump dryer is superior with an average SMER of 2.175 kg/kWh which is 2.22 times greater than that of the electric heater dryer with SMER of 1.224 kg/kWh.

• Journal of computational fluids engineering
• /
• v.20 no.3
• /
• pp.70-78
• /
• 2015

Turbulent flow and heat transfer characteristics of textile machine are numerically investigated. To examine the influence of flow structures on the drying performance of fabrics, the nozzle shape of high temperature chamber is changed. For several nozzles, flow and heat transfer characteristics are discussed. The results show that the drying performance is improved by controlling the angle and arrangement of nozzles corresponding to different drying conditions. This feature is strongly related to the enhancement of turbulent fluctuations and secondary flows.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.21 no.1
• /
• pp.1-8
• /
• 2009

The simulation of a heat pump dryer has been carried out to figure out the effect of air flow rate on the drying performance represented by MER, SMER, and so on. The simulation includes the analyses of one-stage heat pump cycle and simple drying process using the drying efficiency. The heat pump cycle with Refrigerant 134a has been considered. In the dryer, some of drying air from the drying chamber flows through the heat pump system, the rest of air bypasses the heat pump system. The two air flows joins before the drying chamber inlet. The performance parameters considered in the present study are MER, SMER, the temperature and humidity of drying air. Those parameters are compared for different total air flow rate or bypass air flow rate.

• Journal of Biosystems Engineering
• /
• v.6 no.2
• /
• pp.48-57
• /
• 1982

In order to improve the quality of traditionally sun-dried red peppers and to increase the efficiency of drying performance, three types of solar dryers were designed and built, and drying performance of the solar dryers was compared to traditional sun drying. Results obtained from the experiment are summarized as fallows: 1. The air temperature and relative humidity profiles over a 8-hour period measured at the specified locations in the drying chamber of solar dryers appeared to have large variation in each dryer. The rate of drying increased with the temperature rise in the drying chamber of the solar dryer. 2. In general. drying with solar dryers proceeded faster than traditional sun drying. With A'-type of solar dryer developed in the second experiment it was possible to dry red peppers in seven days from an initial moisture content of 80% to safe storage conditions. The drying time with the A'-type solar drier was 50% shorter compared to traditional sun drying. 3. Red peppers appeared to have an increasing or constant-rate drying period until the weight of the product was reduced to about one half the initial weight, followed by a falling-rate drying period. When the dried red peppers were exposed to the atmospere during the night, the moisture content increased as much as 6%, which is much higher than for the grains. 4. It was suggested from the experiment that either a heat storage system or a supplemental heating system in the solar dryer was desirable for more efficient drying operation. 5. It was shown that the solar dryer developed in this study may be suitable for drying other vegetables and fishes, and also offered additional advantages of saving in drying time, maintaining sanitation and minimizing contamination by dust, insects and unfavorable weather condition.