LED照明を用いた展示ケースにおける温湿度分布とその要因について

摘要

三重県総合博物館の大型壁付展示ケースについて，LED照明点灯時の温湿度分布，循環ファンと調湿剤の効果について実測調査を行った。その結果LED照明のみの展示ケースであっても温度上昇が見られ，蛍光灯やハロゲンライトによる照明と同様に，ケースの仕様や展示運用について注意が必要であることが分かった。また調湿剤と循環ファンの導入は高さ方向の温湿度分布の均一化に有効であることが分かった。CFDによる温湿度分布の予測を行った。STREAM~®により展示ケース内の温湿度分布を概ね予測でき，また高さ方向の温度分布の要因を推定することできた。展示ケースの設計や仕様の決定に応用することが期待される。%In the present study, the distribution of temperature and relative humidity inside one of the exhibition cases in the temporary exhibition room of Mie Prefectural Museum due to heat generated from LED lighting devices was measured and their 3D distribution was estimated by computational fluid dynamics (CFD). The effects of installed silica gel humidity conditioner and air circulation system were observed from the measurements, and the main factors of the distribution of temperature were evaluated from the results of CFD. As a result of measurements, it was found that the temperature inside the exhibition case was higher when there was no forced air circulation than when there was. The temperature at 4.5m from floor level was especially high in both circumstances, but with forced air circulation the gradient of temperature distribution was lower in the direction of the height. As to the gradient of relative humidity distribution, no considerable difference was found between the two circumstances. However, the absolute humidity increased more with forced air circulation. It can be presumed that the air controlled with humidity conditioner was delivered more efficiently. Estimations of temperature and humidity distribution by CFD were nearly the same as the results of measurements. From these estimated temperature distribution and air direction by CFD, turbulence of heated air and re-heating were observed at a high position on the exhibition case, and it can be presumed that these phenomena were the main factors for temperature increase when there was no forced air circulation. Even though LED light generates less heat than incandescent or fluorescent light, the temperature inside exhibition case will increase. So we need to be continually careful when setting display lights. Also, for efficient humidity control, it is better that the air inside exhibition case be circulated all the time.