دراسة أداء مبادل حراري أرضي لمنظومة تكييف هواء في بناية سكنية
Study the Performance of a Ground Heat Exchanger for Air Conditioning System in Residential Building
- الباحث
- سيف حميد مجيد
- المشرف
- ضياء غانم - عمار سعدون
- الجامعة
- الجامعة التكنولوجية
- الكلية / القسم
- قسم الهندسة الميكانيكية / الهندسة الميكانيكية
- الشهادة
- ماجستير
- السنة
- 2021
- لغة الرسالة
- انكليزي
- الكلمات المفتاحية
- Ground heat exchanger;Air conditioning;Residential building;Geothermal energy
Abstract
This study aims to investigate the possibility of reducing electricity consumption in air conditioners by using the ground to cool the hot fluid in the pipes. Several practical experiments with mathematical calculations were carried out for studying the systems performance in Baghdad city conditions. The heat exchanger is designed and dimensioned to reach the optimum efficient design. The test rig used two configuration of ground source heat exchanger (GSEX). The first model was coil type with two different materials (copper and PVC), while the second model was 3U type made of (copper, PVC, and galvanize). Soil temperature measurement pipe was used measure the temperature gradient of soil. Three water flow rates considered (5,10,15) l/min with water inlet temperatures (80,70, and 60 °C) Theoretical study was done for different designs of ground source heat exchanger using ANSYS FLUENT 19R3 software. The results of the current study indicated that geothermal energy is a good source of energy that can be used ground source heat exchanger systems in Iraq. At an adequate depth, ground temperature is comparatively stable, lower than the outside air temperature in summer and greater than the outside air temperature winter. Practical measurements showed that the average soil temperatures were (24.2, 23.8, and 23°C) at depths of (3, 3.5, and 4 m), for April, May and June, respectively. Three flow rates of coolant were examined. The practical measurements showed that low flow rates (5 l/min) cause a greater discrepancy between the GSHE inlet and outlet temperature compared with high flow rates (10,and15 l/min). The experiments also showed that the material of pipe has a significant influence on both the efficiency of heat transfer and the performance of the system. Copper tubes were the best type of coil to be used in this regard. The outlet water temperatures were 64, 68.2, 73.5, 76, and 77°C when using a copper coil, 3U copper pipe, 3U galvanized pipe, PVC and 3U PVC pipe, when the inlet water temperature and flow rate were 80°C and (5 l/min). respectively. The rate of heat transfer (Q) increases with increasing temperature difference between the cooling fluid and the soil. The highest recorded values of Q were 5.81, 4.81, 2.72, 1.60, and 1.32 kW at inlet temperature 80°C and flow rate of (5 l/min) for the case copper coil, copper 3U, galvanized 3U, PVC profile, and PVC 3U, respectively. The highest calculated value for coefficient of performance (COP) was 15.72, 12.99, 7.34, 4.33 and 3.58 at inlet temperature 80°C and flow rate of (5 l/min) for copper coil, 3U copper, 3U galvanized, PVC coil, and 3U PVC coil, respectively. The numerical results showed that the theoretical results are in good agreement the experimental ones. The theoretical results concluded that the copper coil has the best performance compared in the other five types and water flow rate (5 l/min) and different inlet temperatures (80, 60, and 60°C). The temperature differences were (18.536, 16.1, and 12.2°C).
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