تجزیه و تحلیل عملکرد و تأیید تجربی از یک استیل لوله ای چند آستین با رسانه گاز مختلف پر شده

A novel nonconcentrical multi-sleeve tubular still for triple-effect solar desalination device is described in this study. An experimental and analytical analysis is given to investigate how the water production performance is affected by different gas media, which are air, oxygen, helium and carbon dioxide. The water production rate and the temperature value of every measured point inside the device with different gas media were obtained through the experiments. Experimental results show that, when the heating temperature is 85 °C and the gas medium is oxygen, the water production rate can reach to 0.58 kg·h− 1. It is increased by 31.82% compared with the rate when the gas medium is air. In addition, the internal heat and mass transfer mechanism of the device with different gas media was analyzed. The semi-empirical expression of the water production rate is given. According to the experimental data, the Dv under different conditions is obtained. The results obtained are then compared against the experimental results, and it is found that the trend of theoretical water production rate is consistent with the experimental results. The reasons for deviation are analyzed.

The tubular still is one of the design options for seawater desalination. Its advantage is a simple structure and pressure-bearing. Shafiul and Teruyuki [1] have analyzed the mechanism of heat and mass transfer of the tubular still under the steady-state condition, and presented a heat and mass transfer model. The model can forecast the water production rate of the device, which was validated by indoor experiment. Murase et al. [2] have carried out both the outdoor and indoor experiments to investigate the performance of the tubular solar still. For the solar intensity of about 17 MJ/m2day, the device can produce 2 kg fresh water per day. Ahsan et al. [3] have studied the influence of different shell materials on the performance of tubular still. They used a vinyl chloride sheet and a polythene film as tubular shell. The experiments of two devices were carried out under the same operating condition. As a result, the fabrication and the water production cost will be reduced when the device with the polythene film is sealed properly, an empirical equation in their study is proposed to predict the hourly production. The empirical equation was verified by the experimental results. It was seen that the calculated results had a good agreement with the experimental data. A lot of researches have been completed in order to improve the water production rate of the still. Dutt et al. [4] designed a slope double stage basin solar distiller, Tiwari et al. [5] designed a slope three-stage basin solar distiller, and Kumar et al. [6] designed a double slope surface and double stage basin solar distiller. These improvements are useful for reusing the latent heat of condensation. By doing this, the energy utilization ratio of the apparatus was raised. Abu Arabi and Reddy [7] have carried out performance evaluation studies for desalination processes that are based on the humidification/dehumidification principle with different carrier gases. This study found that carbon dioxide is the best carrier gas to achieve more fresh water under the same operating conditions. In this paper, with an aim to improve the tubular still on the basis of previous studies, a new nonconcentrical multi-sleeve tubular still is proposed for triple-effect desalination. The device can make full use of latent heat of condensation to give higher energy utilization. The performance of the device filled with different gas media is particularly investigated.

This paper has presented an experimental and analytical study on the effect of different gas media on the water yield of a nonconcentrical multi-sleeve tubular still. It has been found that the heavier gas could increase the water yield rate. For example, when the gas medium in the still is oxygen, the water production rate can reach to 0.58 kg·h− 1 at the operating temperature of 85 °C, which is about 31.82% higher than that for air as the gas medium. At the same operating temperature, the water production rate of the device with carbon dioxide is also higher than that of air. If the gas medium is suitable, the water production may be improved further. Among the four gas media studied, the oxygen seems a good gas medium for a tubular solar desalination device. A gas medium of lower molecular weight such as helium can give a larger diffusion coefficient of vapor. But, it has been found from the experiment that the displacement of helium pushed by the vapor might have counteracted this effect, so helium has not actually increase the water yield rate.