In this experimental study, a heat pump dryer was designed and manufactured, in which drying air temperature was controlled PID. Manufactured heat pump dryer was tested in drying kiwi, avocado and banana from among tr...In this experimental study, a heat pump dryer was designed and manufactured, in which drying air temperature was controlled PID. Manufactured heat pump dryer was tested in drying kiwi, avocado and banana from among tropical fruits and energy and exergy analyses were made. Drying air temperature changed between 40 oC - 40.2 oC while drying the tropical fruits. Before the drying process in heat pump dryer, initial moisture contents were determined as 4.31 g water / g dry matter for kiwi, 1.51 g water / g dry matter for avocado and 4.71 g water / g dry matter for banana. Then tropical fruits were dried separately in heat pump dryer. Drying air temperature was kept unchanged with the error of +0.2 oC. Drying air velocity changed between 0.3 and 0.4 m/s in a period of 310 min. COPws of the heat pump dryer was calculated as 2.49 for kiwi, 2.47 for banana and 2.41 for avocado during the experiments. EUR changed between 13 % and 28 % for kiwi, 18% and 33% for avocado and 13% and 42% for banana in heat pump dryer.展开更多
The optimum drying conditions with regard to minimum color changes, high rehydration ratio and drying rate for chanterelle mushrooms is inadequately known. To address this problem, drying kinetics for chanterelle mush...The optimum drying conditions with regard to minimum color changes, high rehydration ratio and drying rate for chanterelle mushrooms is inadequately known. To address this problem, drying kinetics for chanterelle mushroom samples with sizes of 20 mm×20 mm×20 mm cube, 20 mm×20 mm×30 mm cuboid, and Ø40 mm×20 mm cylindrical shape were experimented. Drying air temperatures of 40℃, 48℃, and 56℃ at superfluous humidity and velocity of 2.2 m/s were used. Initial color pixels for each sample were determined using Note 8 Pro Xiaomi smartphone camera and image processing tool in Matlab R2019a. Triplicate experimentation was done based on L9 Taguchi orthogonal arrays with drying rate, specific moisture extraction rate, color change, and rehydration ratio being the response parameters. The drying rate increased from 1.1174 g/g∙min to 1.3478 g/g.min as the temperature rose from 40℃ to 56℃. The mushroom cube had the highest drying rate of 1.2860 g/g∙min while the cylindrical shape had the lowest rate of 1.1764 g/g∙min. Similarly, SMER increased from 0.006 326to 0.013 27 g/kWh with the temperature rise. Contrary, SMER decreased from 0.006 92 to 0.013 63 g/kWh in cylinder to cube respectively. Color change was highest at 40℃ (13.49) and lowest at 56℃ (11.94). The mushroom cube had the lowest color change of 9.28 on average when compared to other shapes. Rehydration ratio was highest at 56℃ (3.824) as compared to 48℃ and 40℃. Additionally, the mushroom cube had the highest rehydration ratio of 4.55 on average as compared to other shapes. Temperature variation significantly influenced the drying rate and SMER. However, temperature variation had insignificant differences in color change and rehydration ratio. Mushroom shape variation had a significant difference in all the response variables tested. Conclusively, mushroom cubes at the drying temperature of 56℃ gave optimized drying conditions for chanterelle mushrooms with minimal quality deviations. Thus, chanterelle mushrooms can be sliced into cubes to allow quick drying rate, better SMER, rehydration ratio, and have minimal color change.展开更多
Heat pump cycles have been widely applied to dryers for their high efficiency. However, low–efficiency electrical heaters are often used during early drying stage for frozen foods or winter since a standard heat pump...Heat pump cycles have been widely applied to dryers for their high efficiency. However, low–efficiency electrical heaters are often used during early drying stage for frozen foods or winter since a standard heat pump cycle cannot operate at low temperature. This study introduced cascade heat pumps replacing electrical heaters to improve dryer performance at low temperatures. Experiments were performed to examine changes in performance of the cascade heat pump dryers in relation to ambient temperature, low-stage cycle mass flow rate, and high-stage cycle mass flow rate. The results showed a significant improvement in low-temperature dryer performance with the introduction of cascade heat pump cycles.展开更多
A multi functional wood dehumidification dryer has been developed recently. The dryer can carry out air dehumidification by using only one refrigeration system, in which heat supplying and moisture air are exhausted ...A multi functional wood dehumidification dryer has been developed recently. The dryer can carry out air dehumidification by using only one refrigeration system, in which heat supplying and moisture air are exhausted by changing the position of several air dampers. In this paper, the work principles and characteristics of the dehumidification dryer are introduced, and the testing results about the thermal engineering performance of the dehumidification dryer, as well as the experiment results of drying several species of lumbers are expounded.展开更多
文摘In this experimental study, a heat pump dryer was designed and manufactured, in which drying air temperature was controlled PID. Manufactured heat pump dryer was tested in drying kiwi, avocado and banana from among tropical fruits and energy and exergy analyses were made. Drying air temperature changed between 40 oC - 40.2 oC while drying the tropical fruits. Before the drying process in heat pump dryer, initial moisture contents were determined as 4.31 g water / g dry matter for kiwi, 1.51 g water / g dry matter for avocado and 4.71 g water / g dry matter for banana. Then tropical fruits were dried separately in heat pump dryer. Drying air temperature was kept unchanged with the error of +0.2 oC. Drying air velocity changed between 0.3 and 0.4 m/s in a period of 310 min. COPws of the heat pump dryer was calculated as 2.49 for kiwi, 2.47 for banana and 2.41 for avocado during the experiments. EUR changed between 13 % and 28 % for kiwi, 18% and 33% for avocado and 13% and 42% for banana in heat pump dryer.
基金supported by the Jiangsu Special Fund for Innovation and Extension of Agricultural Science and Technology (Project No.NJ2019-15)for supporting this research.
文摘The optimum drying conditions with regard to minimum color changes, high rehydration ratio and drying rate for chanterelle mushrooms is inadequately known. To address this problem, drying kinetics for chanterelle mushroom samples with sizes of 20 mm×20 mm×20 mm cube, 20 mm×20 mm×30 mm cuboid, and Ø40 mm×20 mm cylindrical shape were experimented. Drying air temperatures of 40℃, 48℃, and 56℃ at superfluous humidity and velocity of 2.2 m/s were used. Initial color pixels for each sample were determined using Note 8 Pro Xiaomi smartphone camera and image processing tool in Matlab R2019a. Triplicate experimentation was done based on L9 Taguchi orthogonal arrays with drying rate, specific moisture extraction rate, color change, and rehydration ratio being the response parameters. The drying rate increased from 1.1174 g/g∙min to 1.3478 g/g.min as the temperature rose from 40℃ to 56℃. The mushroom cube had the highest drying rate of 1.2860 g/g∙min while the cylindrical shape had the lowest rate of 1.1764 g/g∙min. Similarly, SMER increased from 0.006 326to 0.013 27 g/kWh with the temperature rise. Contrary, SMER decreased from 0.006 92 to 0.013 63 g/kWh in cylinder to cube respectively. Color change was highest at 40℃ (13.49) and lowest at 56℃ (11.94). The mushroom cube had the lowest color change of 9.28 on average when compared to other shapes. Rehydration ratio was highest at 56℃ (3.824) as compared to 48℃ and 40℃. Additionally, the mushroom cube had the highest rehydration ratio of 4.55 on average as compared to other shapes. Temperature variation significantly influenced the drying rate and SMER. However, temperature variation had insignificant differences in color change and rehydration ratio. Mushroom shape variation had a significant difference in all the response variables tested. Conclusively, mushroom cubes at the drying temperature of 56℃ gave optimized drying conditions for chanterelle mushrooms with minimal quality deviations. Thus, chanterelle mushrooms can be sliced into cubes to allow quick drying rate, better SMER, rehydration ratio, and have minimal color change.
基金supported by Basic Science Research Program through the National Research Foundation of Korea
文摘Heat pump cycles have been widely applied to dryers for their high efficiency. However, low–efficiency electrical heaters are often used during early drying stage for frozen foods or winter since a standard heat pump cycle cannot operate at low temperature. This study introduced cascade heat pumps replacing electrical heaters to improve dryer performance at low temperatures. Experiments were performed to examine changes in performance of the cascade heat pump dryers in relation to ambient temperature, low-stage cycle mass flow rate, and high-stage cycle mass flow rate. The results showed a significant improvement in low-temperature dryer performance with the introduction of cascade heat pump cycles.
文摘A multi functional wood dehumidification dryer has been developed recently. The dryer can carry out air dehumidification by using only one refrigeration system, in which heat supplying and moisture air are exhausted by changing the position of several air dampers. In this paper, the work principles and characteristics of the dehumidification dryer are introduced, and the testing results about the thermal engineering performance of the dehumidification dryer, as well as the experiment results of drying several species of lumbers are expounded.
