کاهش مصرف انرژی در ساختمان ها با سیستم غیر فعال خورشیدی در راستای کاهش مصرف انرژی :

این تحقیق به بررسی ضریب انتقال گرما در استفاده از دو نوع کلکتور خورشیدی در حالتهای مجهز به سپرهای گرمائی و خالی می پردازد. کلکتورها به صورت تک گذر و گذر دوبل میباشند. هوا از فضای داخلی ساختمان به وسیله فن در محدوده اعداد رینولدز ۲۵۰۰ تا ۶۰۰۰ بداخل کلکتورهای فوق دمیده و پس از گرم شدن مجدد بداخل آن برمی گردد.

سپرهای گرمائی در سه گام PR=1    ۱,۳۵     ۲  متر مورد استفاده قرار گرفته است. ضرایب انتقال گرما در کلکتورهای در حالتهای استفاده از سپرهای گرمائی با گام های مختلف و خالی بدست آمده و با هم مقایسه شده است. درصد نسبت ضریب انتقال گرما با استفاده از سپرهای گرمائی مذکور به ضریب انتقال گرما در کلکتور خالی در شرایط استفاده از کلکتور تک گذر به ترتیب ،% ۱۲۴  ،۱۵۲ % و۱۷۱٫۵ % و در شرایط استفاده از کلکتور با گذر دوبل به ترتیب ۱۴۲% ،۱۶۲% و ۱۸۳% می باشند. با  بکارگیری کلکتورهای خورشیدی در ساختمان باعث صرفه جویی مصرف انرژی خواهیم بود.

REFLECTIVE ELECTROCHROMIC DEVICES: ELECTROCHROMIC CAR MIRRORS

Abstract

 Mirrors, which obviously operate in a reflectance mode, illustrate the first application of electrochromism. Self-darkening electrochromic mirrors, for automotive use at night, disallow the lights of following vehicles to dazzle by reflection from the driver’s or the door mirror. Here an optically absorbing electrochromic color is faded over the reflecting surface, reducing reflection intensity and thereby alleviating driver discomfort. However, total opacity is to be avoided, as a muted reflection must persist in the darkened state. The back electrode is a reflective material, allowing customary mirror reflection in the bleached state. A method for retrofitting a window with a developed switchable or non-switchable window was designed to modify conventional glass or plastic windows. By combining such windows with a switchable glazing such as a Suspended Particle Device (SPD) film or with a non-switchable device such as a tinted window in a simple manner, and to the retrofitted windows produced. The method includes providing a window comprising at least one relatively transparent viewing pane with first and second opposed viewing surfaces.

۱۰th International Conference on “Technical and Physical Problems of Electrical Engineering” (ICTPE-2014) Baku, Azerbaijan, 7-8 September 2014

Convection and radiation heat transfer in a tube with core rod and honeycomb network inserts at high temperature

 Abstract

Heat transfer and friction factor characteristics in a circular tube fitted with core rod and honeycomb network inserts at high temperature have been investigated experimentally. In the experiments, ambient air with Reynolds numbers ranging from 6000 to 20,000 is passed through a circular tube with uniform wall temperature. Convection and radiation heat transfer phenomena are studied. The experimental results show that at uniform wall temperatures of 373, 473, 553, and 633 K, the average shares of the radiation heat transfer coefficient to the total heat transfer coefficient are 13.9%, 18.3%, 24.7%, and 28.7% for core rod and 11.5%, 13.1%, 15.3%, and 17.8% for honeycomb network insert, respectively. In addition, the heat transfer coefficient increased by 227%, 299%, 327%, and 369% for core rod and 409%, 529%, 614%, and 679% for honeycomb network insert compared with the plain tube under the aforementioned temperatures

 

Convection and Radiation Heat Transfer in a Tube with Core Rod and Multi Duct Inserts at High Temperature

 Abstract

Heat transfer and friction factor characteristics in a circular tube fitted with core rod and multi duct inserts at high temperature have been investigated experimentally. In the experiments, ambient air with Reynolds numbers in a range of 6000-20,000 is passed through a circular tube with uniform wall temperature and convection and radiation heat transfer phenomena are studied. Experiments have been performed at four constant wall temperature tubes with core rod insert. For each wall temperature considered, convection and radiation heat transfer coefficients have been determined. The experimental results show that at uniform wall temperature of 373 K, 473 K, 553 K and 633 K the average share of the radiation heat transfer coefficient to the total heat transfer coefficient are 11.5, 13.1, 15.3 and 17.8% for core rod and 16.9, 20.0, 24.3 and 27.8% for multi duct insert respectively. In addition it was noted that for the mentioned temperatures, the heat transfer coefficient increased by 227, 299, 327 and 369% for core rod and 279, 396, 453 and 539% for multi duct insert respectively in comparison to the plain tube. It was also noted that increasing the wall temperature also resulted in increase of friction factor. Based on the experimental results for Nusselt number and friction factor empirical correlation have been derived. Plotting the experimental findings and the correlations, it was noted that the majority of the data are within ±۱۲% and ±۸% of the proposed correlations for heat transfer coefficient and friction factor, respectively. The results were also tested against available and well proven correlations with reasonable agreement