遠赤外線加熱の付加による過熱水蒸気処理の伝熱速度および熱効率の改善 <原著論文>

Enhancement of Heat Transfer Rate and Thermal Efficiency by Combining Far Infrared Heating with Superheated Steam Treatment

Isa Akiko

Hagura Yoshio

Suzuki Kanichi

日本食品工学会誌

Enhancing effects of heat transfer rate and thermal efficiency of superheated steam treatment (SHS) combined with far infrared heating (FIH) were compared with those of superheated steam treatment only by using a semi-practical compact apparatus fabricated in this study. Heat transfer rate was calculated from the constant drying rate of samples wetted enough with water. The samples were treated at three superheated steam temperatures (120, 150, and 200°C) or at those temperatures combined with four far infrared heater temperatures (250, 300, 350 and 400°C). When only 1/5 of SHS heat flow was supplied in addition to the FIH heater, the heat transfer rate was increased 2 times or more compared with that for SHS only. Thermal efficiencies for the SHS heating process + 400°C FIH were about 2-4 times larger than those for SHS only, depending on the superheated steam temperature. When a low temperature (about 120°C) with a small amount of steam was combined with high temperature FIH (about 400°C), a highly enhanced effect on both heat transfer rate and thermal efficiency was obtained. Furthermore, the SHS + FIH process greatly reduced the heating up time of the apparatus and the heat flow to maintain a constant temperature in the heating chamber.

遠赤外線加熱を付加した小型の過熱水蒸気処理試験装置を試作し, 過熱水蒸気に遠赤外線加熱を併用した場合の伝熱促進効果および熱効率を過熱水蒸気単独処理の場合と比較した. 3種類の過熱水蒸気温度120, 150, 200℃に遠赤外線ヒータ250, 300, 350, 400℃を組み合わせて加熱処理し, 水で十分に濡れた試料を用いた恒率乾燥速度から伝熱速度を求めた.

過熱水蒸気処理に遠赤外線を付加した場合, 遠赤外線ヒータに加える熱流が過熱水蒸気生成熱流の1/5程度で伝熱速度は過熱水蒸気単独処理の2倍以上となった. 過熱水蒸気の温度によっては, 400℃の遠赤外線加熱を併用した場合の熱効率は, 過熱水蒸気単独処理の約2～4倍以上になった. 蒸気量の少ない低温(120℃程度)の過熱水蒸気に高温の遠赤外線加熱(400℃程度)を併用すれば, 少ない熱流で遠赤外線加熱の付加による高い伝熱促進効果が得られ熱効率も向上した. さらに, 遠赤外線加熱を併用した過熱水蒸気処理では, 装置立ち上げ時間の大幅な短縮や低熱流での加熱処理庫内温度の維持が可能であった.

Super heated steam

Far infrared heating

Heat transfer rate

Thermal efficiency

Manufactures [ 580 ]

jpn

日本食品工学会

[ISSN] 1345-7942

[NCID] AA12076107