การศึกษาและจำลองแบบหาสมรรถนะ ของสระแสงอาทิตย์ชนิดคงเสถียรภาพด้วยเกลือ / ธนาคม สุนทรชัยนาคแสง = A study and simulation of performance of salt-stabilized solar pond / Thanakom Soontornchainacksaeng
This thesis was to study and simulate the performance of the salt-stabilization in a solar pond. The equipment consisted of a solar pond made of concrete o.95 meter in diameter and 1.2 meter in depth. The outside wall as well as the bottom part were covered with fiber-glass insulator of 50 millineter in thickness. The solar simulation heating was utilized to simulate the main heat source. A solar pond was constructed for experiment at the Department of the Mechanical Engineering at Chulalongkorn University. The salt water in the pond was divided into three portions. The first portion was a heat storage zone, about 0.60 meter from the bottom, with 20 % (NaCl) salt concentration. The second portion was a non-convecting zone and it was 0.40 meter up from the first zone. The second portion had 4 layers, each of which was 0.10 meter high, with the portion salt concentration of 16% (NaCl), 12% (NaCl), 8% (NaCl) and 4% (NaCl) respectively. The third top portion was 0.20 meter of fresh water. Comparision of the experimental and calculated results, it was found out that the generated temperature in the storage zone from the program computer calculation was higher than temperature measured in the experiment. When the temperature inside the storage zone reaches sixty degrees celciuss, it was found out that the energy loss from the storage zone is about 19.33 watt per square meter per hour. To maintain the stability of the salt water in the pond, 8% (by volume) or 0.034 m³ of salt was taken out from the zone (the whole volume in this zone was equivalet to 0. 425 m³). Then the salt water was poured out to remain only 0.0305 m³. After that more salt wass added to make up the volume of 0.034 m³ (the whole quantity of added salt was 7.49 kgs). This new salt water was restored into the storage zone again. At the same fresh water was used to was the surface of the salt water on top of the pond, because of the diffusion of salt water from the bottom upward (The quantity of fresh water used was equivalet to 20 Kgs). It was found out that the stability of salt water in the pond lasted 36 days. From this experiment, it was found out that the solar pond gave the thermal efficiency 18.7% at the temperature of 60 °C at the storage zone and the intensity of sunlight falling on this solar pond was equivalet to 348.55 Watt/m².