Introduction
In 2018, air conditioners (ACs) were consuming the highest electricity per percentage of household penetration of 958 GWh/% penetration annually in Indonesia. Moreover, the primary method of electricity generation in Indonesia was coal, generating 58% of energy consumed, followed by natural gas (27%).
By 2023, air conditioners were contributing to 10% of Indonesia’s total carbon emissions of 674.536 megatons, placing Indonesia in the top 10 most polluting countries. Due to the increasing number of AC users, driven by increasing temperatures and economic growth, household penetration of AC is predicted to reach 37% in 2050, contributing to 20% of Indonesia’s total carbon emissions.
This leads to the vicious cycle of AC usage increasing carbon emissions, which contributes to global warming, increasing global temperatures, hence leading to more AC usage.
Furthermore, only 5% of Indonesian households owned ACs in 2018. The majority of ACs were possessed by high-income households. Additionally, Indonesia produces the largest amount of electronic waste in Southeast Asia of 812 kilotons.
Previous studies have been done on thermoelectric air conditioning, such as the study done by International Journal for Research in Applied Science and Engineering Technology. However, the previously mentioned study did not test the cooling effect of the prototype. Moreover, there is no pre-existing research exploring Peltier air conditioning utilizing countercurrent heat exchange and recycled parts.
This study aims to design a solar-powered, recycled air conditioner prototype (Raycycle), tackling 3 pressing issues: high carbon emissions produced by traditional AC usage, low affordability of ACs and Indonesia’s mountain of electronic waste.
This study aims to test whether the prototype can effectively lower temperature, at a lower cost than traditional air conditioners.
Methodology
Mechanism
The prototype utilizes the Peltier effect and counter-current heat exchange.
In the Peltier effect, applying a current across a thermoelectric material produces a temperature gradient. The Peltier module acts as a heat pump— heat is absorbed at the cold side and deposited at the hot side.
Counter-current heat exchange can be seen in several animal species. In King penguins, warm blood flowing away from the heart in arteries passes close to cold blood flowing from the feet, in opposite directions. This allows more efficient transfer of heat from the warm to cold blood.
In concurrent flow, the temperature gradient decreases with distance, while in countercurrent flow, the temperature gradient remains constant. Since heat flow depends on the steepness of the temperature gradient, countercurrent flow facilitates more overall heat exchange.
Baca juga : Daikin Resmi Operasikan Pabrik AC Pertama Di Indonesia
Experimental Procedure
One 30W solar panel was used to directly power one Peltier module. To simplify the experimental set-up, the solar panel was directly connected to the Peltier module, without the solar charger and battery. The experiment was conducted in Jakarta to test the prototype in Indonesia’s tropical climate in July. Digital probe thermometers were used to measure the temperatures of the hot and cold sides of the Peltier module-heatsink complex after the temperatures had become constant. The thermometer was also used to measure the surface temperature of the ground outside for comparison. The investigation was repeated over a range of light intensities, which were measured using the mobile phone application ‘Light Meter’.
Results
Time of day | 09:00 | 12:00 | 13:30 |
Light intensity/lux | 69407 | 124382 | 89927 |
hot side temperature/°C | 31.5 | 37.9 | 37.6 |
cold side temperature/°C | Baca juga : Rebranding, HealthMetrics Resmi Hadir di Indonesia 30.9 | 35.8 | 36.3 |
outside surface temperature/°C | 31.6 | 37.0 | 37.3 |
temperature difference between cold side and outside surface temperature air/°C | 0.7 | 1.2 | 1.0 |
Table 1.2. A table of the temperatures of the sides of the Peltier module and surface temperature of outside ground, at different light intensities, is shown.
Traditional AC | Raycycle | |
Purchase cost/IDR | Baca juga : Telkom Gandeng Thales Dukung Percepatan Pertumbuhan Ekonomi Indonesia 3.750.000-5.650.000 | 705.980 |
Electricity cost per month/IDR | 390.069 | 0 |
Table 1.3. shows the operating costs of a traditional AC compared to the Raycycle. The electricity cost of the Raycycle is IDR 0 as solar energy is freely available during the day. Note that traditional AC costs may vary.
Discussion
From Table 1.2., it can be observed that one TEC1-12703 Peltier module could decrease temperature by 0.7-1.2°C, depending on the time of the day.
Although the temperature drop caused by the Peltier module was small, the cooling effect produced was limited by the number of modules, dormant fans and low solar panel wattage. Additionally, the cold side may have had higher temperatures due to direct exposure to the sunlight.
The fully operating Raycycle prototype with higher wattage solar panels and operating fans has the potential to cool the air to a much lower temperature. The 4 Peltier modules in the fully operating prototype have the potential to cool by more than 4.8 °C (1.2 multiplied by 4).
Moreover, from Table 1.3., it can be deduced that manufacturing the Raycycle prototype saves IDR 3.044.020–4.944.020. Moreover, Raycycle saves IDR 390.069 per month when compared to a traditional air conditioner. Hence, the prototype saves a mean value of IDR 4.384.089 in the first month of usage.
Limitations and Possible Improvements
Due to the financial constraints, only one 30W solar panel was available. Hence, the investigation was limited to testing one TEC1-12703 Peltier module, greatly limiting the cooling effect. Future investigations should use at least 350W of solar power to power the entire prototype. Purchasing 400W of solar panels would cost IDR 679.600, which is still significantly lower than the purchase cost difference between the original prototype and traditional AC. Furthermore, the experiment was only conducted at one location and one time of the year in Indonesia.
Future investigations may use higher-voltage rechargeable batteries to improve the cooling effect of the prototype, and investigate the cooling effect in various cities in Indonesia. Other possible improvements include measuring the cooling effect at various points in the room, fan speed and humidity of the environment. Finally, more accurate thermometers and light meters could be used in future experiments.
Conclusion
In conclusion, this study demonstrates the potential of the Raycycle prototype in cooling air. Analysis of the results showed that the one Peltier module alone could cool up to 1.2°C. Moreover, the Raycycle saves a significant amount of money compared to a traditional air conditioner. Future improvements to the prototype could increase its cooling effect significantly, decreasing dependence on non-renewable energy, reducing electronic waste produced and increasing affordability of ACs for low-income households in Indonesia.
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