The Effects of Fin Spacing and Tube Outer Diameter of Evaporator on System Performance in Heat Pump Tumble Dryers

In heat pump tumble dryers, moisture separates from the laundry and leaves the dryer system at the evaporator. Moist air goes out the drum and enters the evaporator whose outer surface is below the dew point temperature. Air cools and then leaves its moisture. At the airside of the evaporator the wet surface develops and simultaneous heat-mass transfer occurs. Fin-and-tube heat exchangers are used as evaporators in household heat pump tumble dryers. In addition to optimum operating conditions, optimum evaporator geometry can significantly affect system performance. In this study, a model was developed for household heat pump tumble dryer. The model was validated by experimental data collected from the literature. MATLAB software was used in programming, and fluid properties were taken from Refprop software. The model was run with different fin spacing (2–5 mm) and tube outer diameter (6–12 mm) for evaporator, whereas operating conditions and all other geometrical parameters stayed the same. Then, coefficient of performance (COP), moisture extraction rate (MER), and specific moisture extraction rate (SMER) were calculated. As a result, the effects of fin spacing and tube outer diameter of evaporator were determined depending on the input characteristics of the dryer model. In the working range, SMER was changed up to 20% and 15% depending on the fin spacing and the tube outer diameter of evaporator, respectively

The Effects of Gas Cooler Inlet Pressure on System Performance in Heat Pump Tumble Dryers

Heat pumps working with CO2 as a refrigerant have low energy consumptions if right application areas and operating conditions are selected. The use of CO2 in heat pump dryers is feasible if operating temperatures are appropriate. In heat pump dryers working with CO2 according to the transcritical cycle, one of the most important operating conditions is optimum gas cooler inlet pressure, which gives the maximum coefficient of performance (COP). In this study, a model was developed by using MATLAB software for heat pump tumble dryer working with CO2. The model was validated by experimental data taken from existing literature. Then, COP, moisture extraction rate (MER), and specific moisture extraction rate (SMER) were found by running the model at different gas cooler inlet pressures (80–140 bars). All results were calculated in the same geometry for evaporator, gas cooler, and compressor. Thus, effects on the results of variation of the geometrical features were eliminated. Optimum gas cooler inlet pressure was determined as 100 bars for the system with data input to the model. In the optimum gas cooler inlet pressure working condition, SMER increased 24% and 12% by comparison with 80 bars and 140 bars gas cooler inlet pressure, respectively

Optimization of insulation thickness for different glazing areas in buildings for various climatic regions in Turkey

Insulation is one of the most effective methods intended for reducing energy consumption in both heating and cooling of buildings. Selecting the right materials and determining the optimum insulation thickness in building insulation application is an important issue. In 2000, the "Thermal Insulation Requirements for Buildings" was enacted in Turkey, energy saving by limiting the energy amount used for heating in buildings being the target. In this study, the effect of the alteration of windows and exterior wall areas on the heating energy requirement of the building and on the optimum insulation thickness has been examined by using P1-P2 method. The study has been carried out for four degree-day regions of Turkey for various insulation materials, glazing areas, and fuel types; the results have been presented in charts. In the rest of this study, effects of different insulation thicknesses and fuel on fuel consumption and thereby on emissions of pollutants such as CO2 and SO2 are evaluated. For example, in the building where XPS (extruded polystyrene foam) insulation material and natural gas are used and where the ratio of glazing area to exterior wall area is 0.2 (glazing area percentage), energy saving for the four regions has been found to be 13.996, 31.680, 46.613, and 63.071 $/m2, respectively, and the payback period of investment has been found to be 2.023, 1.836, 1.498, and 1.346 years, respectively. The emissions of CO2 are decreased by 50.91% for the cases in which optimum insulation material (XPS) and natural gas are used. The emissions of CO2 and SO2 are decreased by 54.67% for the cases in which optimum insulation material (XPS) and fuel oil are used.Insulation thickness Glazing area Heating energy requirement P1-P2 method Energy saving

Scimitar Syndrome: A Complex Form of Anomalous Pulmonary Venous Return

Scimitar syndrome, or pulmonary venolobar syndrome, is a rare congenital anomaly, in which all the right pulmonary veins drain into the inferior vena cava. In this study, we review the diagnostic features, clinical management, and surgical strategy in the Scimitar syndrome and discuss the significance of new generation diagnostic imaging methods for this rare anomaly. doi: 10.1111/j.1540-8191.2011.01309.x (J Card Surg 2011;26:529-534

Determination of the Thermal Insulation for the Model Building Approach and the Global Effects in Turkey

One of the most important considerations to be considered in the design of energy efficient buildings is the thickness of the insulation to be applied to the building. In this study the existing building stock in Turkey has been investigated depending on parameters such as the height and the area. A model building has been created covering all of these buildings. Fuel emission reduction of combustion system was calculated in the case of insulation applied to this model building. Heat loss of the existing building stock and exhaust emissions and the contribution to the country's economy with the model building methodology are also determined. The results show that the optimum insulation thicknesses vary between 3.21 and 7.12 cm, the energy savings vary between 9.23 US$/m2 and43.95 US$/m2, and the payback periods vary between 1 and 8.8 years depending on the regions. As a result of the study when the optimum insulation thickness is applied in the model building, the total energy savings for the country are calculated to be 41.7 billion US$. And also total CO2 emissions for the country are calculated to be 57.2 billion kg CO2 per year after insulation