Experimental analysis of a solar absorption system with interior energy storage

This study examines experimentally the cooling application of a solar absorption system with interior energy storage that uses two different auxiliary systems. The experiments were performed at Uludag University, Bursa, Turkey on the 3rd and 4th of August 2010 that had the approximately same average outdoor temperature, 31°C. A solar hot water was delivered via a 40 m2 array of flat plate solar collectors that drove a lithium chloride (LiCl) absorption heat pump with a cooling power peak of 20 kW. A solar-powered air conditioning system was designed for heating and cooling in a test room that had a total floor space of 30 m2. Chilled water produced in the evaporator was supplied to the fan coil units, and the heat of condensation and absorption was rejected by means of a wet cooling tower. An electric heater and an air source heat pump were used as auxiliary systems for the absorption cooling application for two different cases when the solar energy was insufficient. Temperature variations were recorded for the absorption machine components, the test room, and the outdoors. The cooling energy, thermal energy, and daily average coefficient of performance (COP) of the absorption system were calculated for two days. Solar absorption cooling was considered for two different auxiliary systems and is presented in this manuscript. The results showed that the daily average COP of the absorption system was 0.283 for Case 1 and 0.282 for Case 2. For both cases, the interior energy storage of the absorption system enabled it to satisfy the cooling demand during the night while solar energy was not available

Minimization of thermal insulation thickness taking into account condensation on external walls

Condensation occurs in the inner layers of construction materials at whatever point the partial pressure of water vapor diffuses and reaches its saturation pressure. Condensation, also called sweating, damages materials, reduces thermal resistance, and by increasing the total heat transfer coefficient, results in unwanted events such as increased heat loss. This study applied minimization of thermal insulation thickness with consideration given to condensation in the external walls. The calculations of heat and mass transfers in the structure elements are expressed in a graphical form. While there was an increase in the required thermal insulation thickness subsequent to an increase in the internal environment’s temperature, relative humidity, and the external environment’s relative humidity, the required thickness decreased with an increase in the external environment’s temperature. The amount of water vapor transferred varied with internal or external conditions and the thickness of the insulation. A change in the vapor diffusion resistance of the insulation material can increase the risk of condensation on the internal or external surfaces of the insulation

Comparision between conventional systems and heat pump systems for energy saving in textile industry by waste heat

Ülkemizin enerji kaynakları açısından dışa bağımlı bir ülke olması yüzünden, enerjinin üretiminden tüketimine kadar tüm evrelerde verimli kullanımı zorunlu kılmaktadır. Bu açıdan enerji tasarrufu oldukça önemlidir. Bugün ülkemizde endüstride, özellikle tekstil endüstrisinde atık ısıdan yararlanmak amacıyla plakalı eşanjörler yaygın olarak kullanılmaktadır. Gelişmiş ülkelerde ise endüstride bir çok uygulamada ısı pompaları yıllardır yaygın olarak kullanılmaktadır. Özellikle düşük sıcaklıktaki atık ısıdan ısı geri kazanımı sağlanmasında öncelikle tercih edilmektedirler. Bu çalışmada, Bursa da yer alan bir tekstil fabrikasından elde edilen gerçek verilerden yararlanılmıştır. Bu fabrikada, boyahaneden 65°C’ de çıkan atık suyun enerjisinden yararlanmak için plakalı ısı eşanjör kullanılmaktadır. Uygulamada plakalı eşanjör yerine ısı pompası kullanılması halinde, her iki sistemin ekonomik analiz yapılmış ve ilk yatırım maliyeti, yıllık enerji tasarrufu ve geri ödeme süreleri karşılaştırılmıştır. Çıkan sonuçlara göre yüksek sıcaklıklarda plakalı e şanjörü kullanmak daha avantajlı görülmüştür. Ancak plakalı ısı eşanjörün 40°C nin altındaki sıcaklıklarda verimsiz çalıştığı bilinen bir gerçektir. Özellikle 40°C nin altında sıcaklıklara sahip atık ısıdan ısı geri kazanım uygulamalarında, ısı pompasının kullanılması daha uygun olacaktır.Since our country is client in point of energy source, every stage of energy from production to consumption effective usage is enforced. In point of this, energy saving is too important. Today, plate heat exchangers have been using widely for recovery heat in industry, especially textile industry in our country. Heat pumps have been using widely in many applications in developed country for many years. They are especially prefered to provide heat recovery from waste heat at low temperature. In this study, we practiced on real data from textile factory in Bursa. Plate heat exchanger is used to benefit waste water heat leaving from dyehouse at 65°C in this factory. When the heat pump was used in stead of plate heat exchanger, economic analysis was achieved in case of using for each two systems and first investment cost, annualy energy saving cost and pay back time were calculated. As a result, using plate heat exchanger is more advantage at high temperature than heat pump but heat pump applications are determined more suitable than plate heat exchanger applications at lower than 40°C

Performance analysis of a re-circulating heat pump dryer

A re-circulating heat pump dryer (HPD) system was designed, constructed and tested at steady state and transient conditions. Refrigerant 134a was used as a refrigerant in this system. The tests were performed to observe behavior of HPD system. So, changes of temperature and relative humidity of drying air through the dryer and heat pump operating temperatures were observed during the drying process and effects of bypass air ratio (BAR) on the system’s parameters as system performance and specific moisture extracted ratio (SMER) at steady state were investigated. The HPD system was also tested to investigate temperatures and relative humidity changes of drying air during drying process on the system’s parameters depend on time. Air flow rate circulated through the HPD system was 554m3/h during the all tests. According to test results, the system’s parameters did not change up to 40% of BAR. Then the COP and SMER values were decreased after 40% of BAR. While SMER values changed between 1.2 and 1.4, COPsys changed between 2.8 and 3.3 depend on BAR. As well as during the drying process, the COP and SMER values were also affected and decreased depend on time