Observation and modeling of dust deposition on glass tube of evacuated solar thermal collectors in Mongolia

A Solar Thermal Application for Mongolian Detached Houses: An Energy, Environmental, and Economic Analysis Based on Dynamic Simulations

“…The dust deposition effects on the performance of the solar thermal collectors are neglected by assuming the glass tubes perfectly clean during the whole heating season; case (2) The dust deposition effects on the performance of the solar thermal collectors are taken into account by means of Equation 2as a function of the operating conditions. Figure 10 indicates the daily average PM10 emissions x i , the daily average wind factor y i (multiplied by 100), the daily average rain rate z 1,i and the daily average snow rate z 2,i measured by the authors in Ulaanbaatar during the period from October 2015 up to May 2016 [28] and used to run the simulations in this study in the above-mentioned case (2) with the dust deposition effects being taken into account. In the same figure, the percentage difference between the daily average glass tube transmittance including the effects of dust deposition τ w,dust (calculated based on Equation 2) and the daily average glass tube transmittance without the dust deposition effects τ w/o,dust (equal to 0.96) is reported as a function of the simulation time according to the experimental values of x i , y i , z 1,i and z 2,i :…”

“…The dust deposition tests were conducted between October 2015 and May 2016 under the real environmental conditions in Ulaanbaatar [28]. The experiments highlighted that the daily glass tube transmittance during the ith day τ i can be estimated by using the following formula:…”

“…where N is the number of experimentally investigated glass tubes (N = 7), S is the wind speed (m/s), w is a factor indicating the wind direction (w=1 if the wind comes from South, South-East or South-West, while w = 0 for the other wind directions), L and Q are empirically-derived constants (L = −0.007 s/m, Q = 0.2 m/s) [28]. Equation (2) was validated against the measured data.…”

“…An empirical correlation for calculating the reduction in light transmittance has been identified. No studies investigating the effects of dust deposition on the performance of evacuated tube solar thermal collectors operating in cold areas with a great deal of air pollution (such as Mongolia) are available in current literature, except the work performed by the authors [28] where a method capable of predicting the dust deposition rate and the related change in transmittance of glass tubes, using weather data, has been developed and validated based on long-and short-term experimental tests performed in Ulaanbaatar.…”

Model Analysis of Solar Thermal System with the Effect of Dust Deposition on the Collectors

“…The dust deposition behavior on glass tubes of an evacuated tube solar collector was investigated by the authors of the current study [15]. The authors conducted long-term dust deposition tests between October 2015 and May 2016; gathered environmental data such as PM 10 , rain, snow, cloud, wind speed, and direction during that period; and modeled daily change in transmittance of the glass tubes.…”