Abstract
We identified the heating characteristics of longwave infrared radiation and the heater employing in order to establish a drying system for agricultural products.
The emissivity of two major types of longwave infrared radiation heaters on the market were 0.9 or larger when the range of wavelength was 3-15μm. It was clear that the surface temperature of a heater changes in proportion to the voltage and that the surface temperature of a panel heater differs largely according to its position. The absorption value of longwave infrared radiation didnot change when the relative humidity of the air was changed.
We also measured the quantity of heat absorbed by the heatreceiving plates of different hues. In the case of longwave infrared radiation, hue and especially color lightness did not affect the quantity. On the contrary, when an infrared radiationlamp was used, the quantity decreased as colorlightness increased.
The result of measurement of the decomposition rates of β-carotene and chlorophyll-a showed thatthe rate is lower when heated by longwave infrared radiation than when heated by solar or infrared radiation lamp.
