This paper presents an experimental study of wall atomizer usage in flashing purification. The water jet bursts out of the nozzle and hit the wall atomizer, split into particles and evaporate until finally condense. The effectiveness of water particles evaporation influences condensates volume. In this paper, improvements were more focused on how to generate water particles by applying wall atomizer in a flashing chamber. The more water particles were raised, the better the evaporation and condensation rate. Flashing purification experiments were conducted by following the factorial design method. From the first experiment design, an optimum condensate volume is obtained at a specified folding width of wall atomizer and feedwater pressure meanwhile, vacuum pressure and feedwater temperature were kept constant. Three different folding widths of 5mm, 8mm and 12mm were tested in this experiment. The second experiments were continued by varying feedwater temperature at an optimum atomizer folding width to obtain more condensate volume. Wall atomizer usage in flashing purification has been proved to increase condensation rate or condensate volume. The highest condensate volume of 150.2ml was obtained from 8mm atomizer folding width with a combination variable of 2.0 bar-g feedwater pressures, the vacuum pressure of −53 cmHg and feedwater temperature of 70 °C. This result was in line with the theory which states that the presence of a wall atomizer increased water particles. There was even an atomizer folding width which provided an optimum condensate volume. The use of atomizer folding width of less and more than 8mm produced lower condensate volume. At 5mm atomizer folding width, condensate volumes were 24.6ml and 22.0ml, whereas 12mm atomizer folding width produced 48.9ml and 50.3ml.

Purpose: The paper aims to apply Buckingham Pi dimensional analysis method for assessing direct evaporative cooler performance with a cooling pad made of banana midrib and ramie fiber. The saturation efficiency acted as the indicator performance of the evaporative cooler.Design/methodology/approach: The paper describes an experimental study of the direct evaporative cooler with a cooling pad made of banana midrib and rami fiber. There were six parameters in the experiment: absorbed water as a dependent variable was affected by independent parameters such as air velocity and temperature, cooling pad cross-section area and thickness. Based on these variables, we arranged three dimensionless numbers and their correlation.Findings: The paper provides three calculated dimensionless numbers plotted on a curve with a specific correlation. The curve trends for 30 mm and 50 mm pad thickness were almost similar. The range of Reynolds number for 10 mm pad was narrower than other pad thicknesses. The thicker the cooling pad, the more extensive was the calculated Reynolds number range. A new curve exhibited the relationship between the evaporation rate with the μA/t number. The broader cooling pad cross-section, the thinner pad thickness, and the lower pad temperature were factors that increased the evaporation rate, even though the increase was less significant.Originality/value: A new material in cooling pad from banana midrib fiber was tested and compared to ramie fiber and conventional cooling pad.

The flashing process is a way of exposing water in a low-pressure environment by spraying it at high pressure so that the water converts into fine particles. This process is carried out to speed up the evaporation process of water. The evaporation process carried out on freshwater aims to separate the minerals and solids dissolved in water to increase its purity. In this study, the flashing process was carried out through a rotating nozzle that was proven to increase the rate of pure water production. The flashing process experiment is carried out following an experimental design based on the non-dimensional analysis of Buckingham's pi. The rate of pure water production (ṁ_cond) as the output variable in the flashing process is affected by the nozzle rotational speed (n), nozzle hole diameter (d), feedwater pressure (P_w), vacuum pressure (P_v) and feedwater temperature (T). The feedwater temperature itself can influence the behavior of the feedwater flow in the nozzle, in this case, is density (ρ) and viscosity (μ). Based on these variables, the non-dimensional analysis of Buckingham pi has produced four dimensionless numbers. The generated empirical equations from the flashing process experiments are in the form of quadratic equations. The empirical equation applies to feedwater pressure of 7.6 bar-g, the vacuum pressure of 0.4–0.6 bar-a and nozzle rotational speed of 0–134 rpm. The optimum condensation rate in the flashing experiment was successfully obtained, especially at the nozzle rotation of 27 rpm in all vacuum pressures tested. This success is inseparable from the use of mist-nozzles that convert the feedwater flow into the mist.

This research is motivated by the problem of lack of clean water in remote areas such as coastal/sea and riverside/estuary areas. Apart from wells, some people also use river water for bathing and washing toilets. Water's low level of hygiene is almost ignored as long as it can still be used to meet daily needs. To overcome this problem, this research proposes a method to convert feed water or brackish water into clean water. The purpose of this study is to investigate an evaporation method to increase clean water production by adding a water mist system to the solar collector. With the discovery of a method to increase clean water production from the purification of feed water, this research makes a small contribution to improving public health, especially communities around the sea coast. This research was carried out using an experimental method referred to as factorial design method. From the experiment, the ratio of clean water production to the feed water flow rate is 7.9%. The maximum clean water production is 5.78ml/minute or 1.25% of the feed water flow rate when using 4 nozzles in the chamber.

This paper presents an experimental study of heat pump water heater, which is compared with electric and gas-fired water heaters in energy consumption and operating cost. In a heat pump water heater, electricity consumption is proportional to the air conditioning operating cost incurred due to air conditioning while cooling the room. On the other hand, there is a heating effect from a condenser that simply discharged as waste heat to the environment. This study is aimed at analyzing the heat pump water heater's performance by adding a new condenser and comparing the operating cost with two other water heaters. The operating cost of the three water heaters is calculated by testing the devices directly. The test of each water heater is to measure the rise of hot water temperature with different volumes of heated water and energy consumption. The experimental results in the heat pump water heater's heating rate are 0.6°C/min, i.e., lower than in the electric and gas-fired water heaters, which have a 2.6°C/min heating rate. The operating cost average of heat pump water heater is Rp 2214.00 per hour, by 6% lower than that of an electric water heater, and by 38% higher than that of a gas-fired water heater. The study finds that the heat pump water heater's operating cost slightly decreased to the heated water volume. It has an advantage when running the heater at a higher capacity of heated water.