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Günümüzde artan enerji güvenlik problemi, beraberinde çevreye olumsuz tesiri olan sistem tasarımlarını ortaya koymuş olsa da temiz enerji sağlayan sistemler zamanla ön plana çıkmıştır. Soğurmalı soğutma sistemleri elektrik tasarruflu sistemler olduklarından buhar sıkıştırmalı sistemlere göre elektrik tüketimini en aza indirgerler. Bu sistemler sistem performansını arttırmak üzere yarım, tek, çift ve üç kademeli olmak üzere tasarlanabilmektedirler. Kademe sayısındaki artış, soğurma sistemlerini daha verimli hale getirmekle beraber sistem bileşeni sayısını arttırarak daha karmaşık ve hassas sistemlerin kontrol edilmesine yol açmaktadır. Bu çalışmada, lityum bromür-su eriyiği ile çalışan üç kademeli seri akışlı bir soğurmalı soğutma sisteminin termodinamik analizi Engineering Equation Solver (EES) programı yardımıyla yapılmış ve elde edilen benzetim sonuçları literatürle doğrulanmıştır. Enerji ve ekserji soğutma tesir katsayısının (STK ve ESTK) düşük basınçlı kaynatıcı sıcaklığının artmasıyla birlikte arttığı, orta basınçlı kaynatıcı ile yüksek basınçlı kaynatıcı sıcaklıklarının artmasıyla beraber azaldığı görülmüştür. Yoğuşturucu ve absorber sıcaklıklarının artmasının STK'ya olumsuz etki yaptığı görülmüştür.

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The building sector consumes a significant portion of global energy use. In this regard, this work was undertaken to study the status of energy efficiency and conservation at a large school building in the northern part of United Arab Emirates (UAE). The annual electrical consumption at the school was analyzed and an awareness survey among the students and teachers was conducted to measure the level of awareness as well as to assess the current energy consumption practices. In order to identify energy saving opportunities, an energy audit was carried out wherein the school energy consuming systems, particularly the lighting and air-conditioning systems, were assessed. Furthermore, thermography scanning of the school building envelope was conducted to examine the building insulation and identify air leakage locations. The building electricity supply and distribution systems were assessed using power analyzer and thermography devices. The energy conservation measures identified include removing the extra lighting, installing motion sensors in classrooms and labs, as well as integrating a Networked Optimization Software with the current HVAC (heating, ventilating and air conditioning) system. The methodology consists of seven fundamental steps: (1) case study data collection (analysis of buildings and utility data); (2) survey of real operation conditions; (3) understanding of building behavior; (4) analysis of energy conservation measures; (5) estimation of energy-saving potential; (6) economic assessment; and (7) proposing Energy Conservation Measures (ECMs). In this regard, the school energy consuming systems (lighting, building envelope, and air conditioning (AC)) were examined to identify possible ways to reduce the school energy consumption. The results indicate that the cost of installing motion sensors in classrooms, and labs is approximately AED 20,000 (United Arab Emirates Dirham), which yields an annual energy saving of AED 93,691. Furthermore, with all energy saving measures, a total annual saving of AED 364,000 is anticipated, which is approximately 16% of the annual electricity bill.

Original scientific paper https://doi.org/10.2298/TSCI181105068C This paper investigates the factors affecting the optimum insulation thickness and its pay-back period, such as heating and cooling energy requirements of building, lifetime, present worth factor, costs of insulation material and installation, costs of energy sources for heating and cooling, heating and cooling system efficiencies, and solar radiation. For this purpose, by considering two cities characterizing the hot and cold climatic conditions, the optimum insulation thickness and its payback period have been calculated and a detailed parametric analysis has been carried out. To achieve practical results, the ranges of the parameters considered in the study include the values typically reported in the literature. The variations in the optimum insulation thickness and the pay-back period with all parameters are presented in graphical form. Finally, order of importance and contribution ratios of the examined parameters on the optimum insulation thickness are determined with the help of Taguchi method. It is found that heating degree-days is the most efficient parameter on the optimum insulation thickness with an impact ratio of 27.33% of the total effect while the least efficient parameter is the efficiency of heating system with an impact ratio of 3.21%.