An experiment has been carried out for examining the performance of an air conditioning unit under constant outdoor wet-bulb temperature and varied dry-bulb temperature. During the experiment, the wet-bulb temperature of the compartment for outdoor unit was maintained at 22℃ and the dry-bulb temperature was varied from 24℃ to 36℃. The increase of outdoor air temperature results in the increase of supply air temperature, discharge temperature, suction temperature, and liquid line temperature. These cause the degradation of the air conditioner performance. An increase of power consumption by 1.4% and decrease of cooling capacity by 0.8% were observed for each 1℃ increase of outdoor air temperature. As a result, the energy efficiency ratio drops by 2% for each 1℃ increase of outdoor air temperature.
The aeroponic plant root environment has a significant role in producing high-quality seed tuber potatoes. However, in lowland and tropical regions, the aeroponic system cannot yield high-quality potato seed because the average environment temperature year-round is high. In a high-temperature environment, the potato plant roots cannot optimally absorb the nutrient solution for healthy plant growth. This paper presents the method used to maintain the aeroponics root chamber temperature conditions. An air conditioning system was adopted to supply air with the optimal temperature range for mini-tuber potato seed cultivation. The vapor compression refrigeration type was applied in the air conditioning system. The root chamber temperature is controlled and monitored using an Arduino Uno board system. The mini-tuber potato seed cultivation field experiment results show the proposed method can maintain the aeroponic root chamber temperature. The root chamber temperature treatment operated in the 10 °C–20 °C range. This temperature range improved the potato seed tuber yield. The potato seed tuber yield potential is observed from the stolon number produced by the mini-tuber potato plants cultivated in the root chamber with the conditioned temperature. The field experiment reveals that the stolon number produced by potato seeds cultivated in the root chamber with conditioned temperature was up to 77% greater than the number of potato seeds cultivated in the root chamber with the unconditioned temperature.
Propane R-290 as hydrocarbon refrigerant has more benefits from the aspect of thermophysical properties, but the only weakness from this refrigerant is flammable. The distribution prediction of R-290 leakage to an air-conditioned room. The study using numerical simulation of CFD ANSYS FLUENT V.13. The distribution of R-290 with a leakage rate of 0,001kg/s and an airflow of 0,1m/s will run out after 600s, with 0,002kg/s will run out after 300s and with 0,005kg/s and 0,5m/s will run out after 120s. The mass flow rate can influence the refrigerant distribution of leakage effect flowrate. Airflow can increase the dispersion of refrigerant gas and decrease the level of the refrigerant amount at any certain point in the room after the refrigerant charge is empty. This momentum effect was due to the impact of supply air initial velocity. The buoyancy effect was due to R-290 density is greater than the air makes the refrigerant flows downward, accumulated, and stagnant. Make sure that the contactor relays and other electrical tools have the position, x=0 m ≤ x ≤ 1 m on y=0 m ≤ x ≤ 26 m and then y=1 m, x=0 m ≤ x ≤ 4 m.
Propane (HC-290) is one of hydrocarbons often called as a green refrigerant. As a result, in the long term, this refrigerant is able to be used as a substitute refrigerant to HCFC-22. Generally, the amount of charging HC-290 to replace HCFC-22 based on the density ratio of the refrigerants, for instance, the ratio of liquid density at-10°C between HCFC-22 and HC-290 is 40.59%. Also, most investigations reported that the refrigeration system performances of HC-290 were better compared to HCFC-22 without varying the refrigerant charging of HC-290. By varying the refrigerant charging of HC-290 in a freezer, the performances can be optimized. This study presents an experimental investigation of the impacts on the performances of a freezer when the refrigerant charging of HC-290 is varied replacing HCFC-22. Three performances are reported in the present study, namely: cooling capacity, input power and COP. The first experiment was performed on a freezer using HCFC-22 as working fluid and the amount of refrigerant charging was 450 gram. Furthermore, the tests were carried out using HC-290 with six charging conditions: viz.: 30, 35, 40, 45, 50 and 55% of the mass of HCFC-22. The results showed that when refrigerant of HC-290 was charged 45% (mass) of HCFC-22, the freezer yielded the biggest increase in the cooling capacity and COP.
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