Keywords: Air conditioning, solar concentrator, thermosyphon, stirling, inverter, electric
By: Wibawa Endra Juwana, Heru Sukanto, Thoharudin
The onjective of this research is to build air conditioning machine with cheap operasional cost. The step was taken by developing electric generation driven by solar power using Stirling-thermosyphon motor system which was completed by developing DC generator and electric storage equipment. The research was carried out within several steps and started from manufactur of parabolic solar concentrator (PSD) equipped with solar tracking. The heat from solar concentrator was used to boil water and the boiled water was used as driving of Stirling motor. The water boiler was equipped with thermosyphon which serves as heat exchanger for low temperature heat recovery. The shaft of Stirling motor due to its low speed then was accelerated by using pulley arrangement and drive electric generator. The generated electric was saved in accumulator and then converted into alternating current (AC) by using inverter. The electric from inverter was used for compressor of air conditioning machine.
From the experiment can be conluded that the solar concentrator at diameter 2,5 m was able to supply the averave power of 3,462 W/day. The average eficiency of solar concentrator was 44%. The average efficiency of thermosyphon was 22-68% depend casino on working fluid presure, thermosyphon evaporator temperature and air velocity flowing at condencor side of themosyphon. The efficiency of Stirling motor was 17% at water vapour pressure of 2 barg and 21% at water vapour pressure of 3 barg. This research was also success to develop the accumulator charger with efficiency higher than 90% and inverter with efficiency of 75%. By using HCR 134a as refrigerant, have been successful to develop air conditioning machine with capacity of 900 W, COP 2.8, and EER (energy efficiency ratio) of 2.4. Using two solar concentrators and at midday with average solar intensity about 694 W/m2, then all required electric power can be fulfilled. Although the operational cost of the air conditioning machine was very low, unfortunately the complete equipment of this air conditiong machine driven by solar power was still very complex.