scholarly journals Experimental study of infrared – assisted heat pump drying of lime slices

2021 ◽  
pp. 1-10
Author(s):  
Nguyen Minh Ha ◽  
Ha Anh Tung
Keyword(s):  
Heat Pump ◽  
Radiation Intensity ◽  
Infrared Radiation ◽  
Effect Of Temperature ◽  
Air Velocity ◽  
Drying Time ◽  
Infrared Radiator ◽  
Chamber Temperature ◽  
Heat Pump Drying ◽  
Drying Chamber

This paper describes the experimental drying of lime slices using an infrared –assisted heat pump dryer. Experiments were carried out on a heat pump dryer model with a capacity of 1 HP integrated with 2000 W infrared radiator whose power can be varied from 0% to 100%. Experiments have been performed with the drying capacity of 1,2 kg/batch and the drying air velocity of 1,2 m/s. Three evaluations were considered: the effect of material thickness on drying time; the effect of temperature in drying chamber and intensity of infrared radiation on drying time, power consumption and product quality. The results showed that the drying process having 3 mm thickness of lime slices, the temperature in the drying chamber of 42,5¸45oC and the radiation intensity of 110¸300W/m2 was the good effective drying range. In addition, the study formulated a linear regression equation for the drying time relationship with drying chamber temperature and infrared radiation intensity. This mathematical model can be used as reference to determine actual drying time as well as a helpful tool for designing infrared - heat pump dryer.

scholarly journals A combined infrared/heat pump drying technology applied to a rotary dryer

2002 ◽  
Vol 11 (3) ◽  
pp. 209-218 ◽  
Author(s):  
K. PÄÄKKÖNEN
Keyword(s):  
Heat Pump ◽  
Infrared Radiation ◽  
Crop Production ◽  
Quality Parameters ◽  
Small Scale ◽  
Rehydration Ratio ◽  
Drying Time ◽  
Operation Temperature ◽  
Rotary Dryer ◽  
Heat Pump Drying

The short drying time and low product temperature makes it suitable for drying such heat-sensitive materials as herbs and vegetables. The purpose of this work was to develop a small-scale dryer for herbs and vegetables. A prototype rotary dryer combining infrared radiation with a so-called heat pump drying method was applied in drying experiments for several herbs and vegetables. The drying experiments were performed under actual crop production conditions. The drying curves for leaves of birch (Betula spp.), rosebay willowherb (Epilobium angustifolium) and dandelion (Taraxacum spp.) as well as slices of red beet (Beta vulgaris) and carrot (Daucus carota) are presented. During the drying operation, temperature and humidity of the drying air were recorded, as well as the energy consumed in drying. The quality parameters measured were water content, colour and rehydration ratio. In the present rotary dryer design, intermittent irradiation and mixing of the product enable to avoid overheating, which is particularly important for maintaining product quality. In this dryer design the drying drum slowly rotates and simultaneously mixes the product. The infrared heaters are attached to a panel, allowing the product to receive infrared radiation periodically.

scholarly journals Drying kinetics and quality aspects during heat pump drying of onion (Allium cepa L.)

2012 ◽  
Vol 1 (2) ◽  
Author(s):  
Nihar Ranjan Sahoo ◽  
Uma Sankar Pal ◽  
Sanjaya Kumar Dash ◽  
M.D. K. Khan
Keyword(s):  
Heat Pump ◽  
Air Temperature ◽  
Colour Change ◽  
Coefficient Of Determination ◽  
Drying Time ◽  
Hot Air ◽  
Thin Layer Drying ◽  
Quality Aspects ◽  
Heat Pump Drying ◽  
Air Dryer

A prototype heat pump dryer has been developed for drying of fruits and vegetables at low temperature and relative humidity to maintain the quality of dried product. Onions, of Nasik red variety were peeled, trimmed and sliced to 2 mm thickness. The onion slices were dried in the heat pump dryer at 35ºC (32 % R.H.), 40ºC (26 % R.H.), 45ºC (19 % R.H.) and 50ºC (15 % R.H.). Samples were also dried in a hot air dryer at 50ºC (52 % R.H.) for comparison. The drying rate increased with increase in drying air temperature, associated with reduced R.H., in the heat pump dryer. Drying took place mainly under the falling rate period. The Page equation, resulting in a higher coefficient of determination and lower root mean square error, better described the thin-layer drying of onion slices than the Henderson and Pabis equation. Heat pump drying took less drying time of 360 min and yielded better quality dried product, with higher retention of ascorbic acid and pyruvic acid and lower colour change, as compared to a hot air dryer at the same drying air temperature of 50ºC.

A Mathematical Model for Thin-Layer Drying of Litchi Pulp

2012 ◽  
Vol 192 ◽  
pp. 51-56
Author(s):  
Zhi Qiang Guan ◽  
Xiu Zhi Wang ◽  
Min Li ◽  
Xiao Qiang Jiang
Keyword(s):  
Experimental Data ◽  
Thin Layer ◽  
Heat Pump ◽  
Moisture Ratio ◽  
Drying Time ◽  
Page Model ◽  
Thin Layer Drying ◽  
Drying Models ◽  
Heat Pump Drying ◽  
Predicted Values

A drying experiment of litchi pulp was done with a self-built heat-pump drying system. A few commonly-used thin-layer drying models for foods were linearized and fitted with the drying experimental data to select a relatively optimal model of depicting the relationship between moisture ratio and drying time of the heat-pump drying of litchi pulp. It was found that the Page model is relatively optimal. The multivariate linear regression approach was employed to solve for the parameters of the Page model based on experimental data and an experimental verification was conducted; the verification results show that the predicted values of the Page model have a good fitness with the measured values and thus the Page model can predict more accurately the moisture ratio and drying rate of litchi pulp in a heat-pump drying process.

scholarly journals ENERGY SAVING TECHNOLOGIES FOR DRYING OF HEAT-SENSITIVE MATERIALS

2019 ◽  
Vol 41 (4) ◽  
pp. 5-12
Author(s):  
Yu.F. Sniezhkin ◽  
Xiong Jian ◽  
D.M. Chalaev ◽  
М.М. Ulanov ◽  
N.О. Dabizha
Keyword(s):  
Heat Pump ◽  
Thermal Conditions ◽  
High Energy ◽  
Heat Pumps ◽  
Convective Drying ◽  
Drying Time ◽  
Long Duration ◽  
Heat Pump Drying ◽  
Promising Development

The promising development of convective drying of thermolabile materials is the use of heat pumps. The main advantages of heat pump drying are high energy efficiency, controlled thermal conditions of drying, high quality of the final product, environmental cleanliness of the technological process.The processes of air treatment in convective heat pumps with different schemes of dehydration of the drying agent are considered in the paper. As determined, the main disadvantage of heat pump drying is the long duration of the process due to the drying temperature limitation not exceeding 50-60 °C, and the dried material is not initially heated above the temperature of the wet thermometer, which is 25-30 °C. The possibility of using infrared radiation in combination with a heat pump was studied to intensify the process of low-temperature convective drying. It is shown that the combination of heat pump and infrared drying processes provides a synergistic effect, which leads to a shorter drying time and reduced energy consumption, as well as to obtain better quality dried products.

Development of a Compact Vacuum Freeze Drying for Jelly Fish (Schypomedusae)

2012 ◽  
Vol 58 (2) ◽  
Author(s):  
M. Idrus Alhamid ◽  
M. Yulianto ◽  
Nasruddin M. ◽  
Engkos A. Kosasih
Keyword(s):  
Heat Loss ◽  
Freeze Drying ◽  
Moisture Ratio ◽  
Cold Trap ◽  
Chamber Pressure ◽  
Internal Cooling ◽  
Drying Process ◽  
Drying Time ◽  
Chamber Temperature ◽  
Drying Chamber

A new design of a vacuum freeze drying with internal cooling and heater from condenser’s heat loss was built and tested. The dryer was used to dry jelly fish (scyphomedusae) to study the effect of drying parameter such as temperature within the drying chamber on mass losses (evaporation) during freezing stage and moisture ratio at the end of drying process and also the drying rate of vacuum drying process. The cold trap temperature rise in when activated the heating from condenser’s heat loss. The midili thin layer mathematical drying model was used to estimate and predict the moisture ratio curve base on different drying chamber temperature. The result of this experiment show that mass loss during freezing stage decreased with a decrease in drying chamber temperature with constant pressure. Drying time reduced with an increase in drying temperature. Drying chamber temperature decreasing has a result pressure saturation of material lower than drying chamber pressure have an effect mass transfer should not occurs.

scholarly journals Effect of Temperature at Tray Position on Drying of D.ark Re.d Oni.on-slice.s at Elevated Air Velocity

2020 ◽  
Vol 9 (4) ◽  
pp. 293-296
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Moisture Ratio ◽  
Convective Drying ◽  
Flow Rate Ratio ◽  
Effect Of Temperature ◽  
Drying Process ◽  
Air Velocity ◽  
Drying Time

The convective drying process is used to dry onion-slices. The drying experiments are conducted at a drying temperature of 50oC, 60oC, 70oC, and at an air velocity of 1.99, 3.54, 5.66, and 7.52 m/s. The objective is to study the influence of tray position on drying of dark red onion. The work diverges in analyzing drying constants at air velocity beyond 2 m/s. The moisture ratio for the middle tray is greater compared to the top and bottom tray. A smaller moisture ratio is observed for 60°C compared to 50 and 70°C. Moisture removal per unit mass flow rate ratio is lowest observed for bottom tray with 60°C. The ratio of moisture content and mass flow rate for 60 and 70 °C, displays a downward trend with drying time. The randomness in the drying rate at 60 °C and 70 °C is comparatively lesser than 50 °C.

scholarly journals Pengaruh kecepatan udara dan massa gabah terhadap kecepatan pengeringan gabah menggunakan pengering terfluidisasi

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
S. Syahrul ◽  
M. Mirmanto ◽  
S. Romdani ◽  
S. Sukmawaty
Keyword(s):  
Moisture Content ◽  
Initial Moisture Content ◽  
National Standards ◽  
Drying Process ◽  
Air Velocity ◽  
Drying Time ◽  
Grain Processing ◽  
Grain Moisture ◽  
Time Required ◽  
Drying Chamber

Grain processing does not meet the actual grain harvests. This is due to the unsuitable drying process. Milling grain entrepreneurs and farmers in Indonesia are currently conducting a drying process under the sun. Based on the National Standards Body (BSN), grain moisture content must be at 14% to maintain the grain at high qualities. The purpose of this study is to determine the effect of velocity and grain mass variations on drying times. The grain used in this study contains an initial moisture content of 22% ± 0.5%. The grain is dried by inserting it into the drying chamber and varying the air velocities and grain mass. The air velocities used are 4 m/s, 5 m/s, 6 m/s and the variations of the grain mass are 1 kg 2 kg and 3 kg. The results show that increasing the air velocity decreases the drying time. On the other hand, when the grain mass is increased, the drying time elevates. The air velocity and mass of the grain that results in the fastest drying time are 6 m/s and 2 kg. The time required for achieving the water content of 13.6% is 30 menit. At the air velocity of 4 m/s, and the grain masses of 1 kg, 2 kg, and 3 kg, to achieve moisture contents of 13.4%, 13.5% and 13.4% the drying time needs 50 minutes.

Solar-Assisted Heat Pump Drying of Coriander: An Experimental Investigation

2018 ◽  
Vol 26 (04) ◽  
pp. 1850037 ◽  
Author(s):  
Abbas Alishah ◽  
Mohammad Valizadeh Kiamahalleh ◽  
Fereshteh Yousefi ◽  
Anita Emami ◽  
Meisam Valizadeh Kiamahalleh
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
Solar Collector ◽  
Coefficient Of Performance ◽  
Air Flow Rate ◽  
Drying Time ◽  
Air Temperatures ◽  
Moisture Extraction ◽  
Heat Pump Drying ◽  
Time And Energy

In this study, the solar-assisted heat pump dryer was designed, manufactured, tested and optimized for drying operations of coriander for its preservation. The heat of drying was mainly provided by a solar collector and a heat pump with two experimental modes of turned on and off. The air temperatures and velocity were identified as the critical drying variables. The responses of the experiments were evaluated in terms of coefficient of performance (COP), energy consumption and the specific moisture extraction rate (SMER). Dehumidification of coriander from the moisture contents of 0.9 to 0.1 kg/kg was considerable. The results demonstrated that utilizing heat pump noticeably decreases the drying time (down to [Formula: see text]25%), energy consumption (down to [Formula: see text]12%) and increases SMER (up to [Formula: see text]20%). The increasing of air flow rate and air temperature significantly led to decreasing the drying time and energy consumption, however, increasing the COP and SMER.

scholarly journals Experimental Assessment of the Thermal Performance of a Heat Pump Dryer System Based on the Variations in Compressor Discharge Pressure on Oregano Drying

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6333
Author(s):  
Arley Salazar-Hincapié ◽  
Alvaro Delgado-Mejía ◽  
Andrés Felipe Romero-Maya ◽  
Eduardo Duque-Grisales
Keyword(s):  
Heat Pump ◽  
Coefficient Of Performance ◽  
Drying Time ◽  
Drying Temperature ◽  
Baseline Case ◽  
Moisture Extraction ◽  
Drying System ◽  
Heat Pump Drying ◽  
Discharge Pressure ◽  
Time And Energy

The current study shows an empirical analysis to establish the effects of the variations in compressor discharge pressure on the drying performance of aromatic herbs, in terms of the coefficient of performance (CoP), moisture content (MC), specific moisture extraction rate (SMER), drying temperature, drying time and energy consumption. In conducting the research, a heat pump drying system was utilized as a mechanism for dehydrating herbs, seeds, and fruits. It was used thanks to its benefits like higher efficiency and its low power consumption. Three levels of discharge pressure were considered, 1380 kPa, 1100 kPa, and 827 kPa, using 1,1,1,2-tetrafluoroethane (R134a) as a refrigerant and oregano leaves as the main product. The findings show that, concerning the same oregano moisture sample, the lower the compressor discharge pressure, the lower drying temperature, also, the higher drying time was obtained. Despite the fact that the CoP decreased with the compressor discharge pressure, in comparison with the baseline case, it remained essentially the same for the other two cases.

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