Construction of a Simple Domeless Net Radiometer for Demonstrating Energy Balance Concepts in a Laboratory Activity

Even though energy balance concepts are fundamental to solutions of problems in a number of disciplines in the agricultural and life sciences, they are seldom demonstrated in a laboratory activity. Here, we introduce a simple domeless net radiometer to demonstrate how the surface temperature of an object aboveground is regulated by the properties of the surfaces and environmental conditions. The device is based on the early designs of all-wave net radiometers and is composed of a foam disc with its opposing surfaces coated with either white or black paint. Temperatures of the disc’s surfaces are monitored using thermocouple temperature sensors. Using a combination of solar irradiance, albedo of the ground surface, air temperature, and wind speed measurements, the temperatures of the disc’s surfaces can be calculated by means of an energy balance model. We found good agreement between calculated and measured temperatures. In addition to demonstrate important physical concepts under natural outdoor conditions, we believe that the proposed laboratory activity will benefit students by allowing them to gain some experience and practical skills in working with environmental sensors, programming data acquisition systems, and analyzing data. Stimulating students’ creativity as well as developing their analytical and problem-solving skills is another goal of the proposed activity.

Silicon Particles/Black Paint Coating for Performance Enhancement of Solar Absorbers

The availability of fresh drinkable water and water security is becoming a global challenge for sustainable development. In this regard, solar stills, due to their ease in operation, installation, and utilization of direct sunlight (as thermal energy), promise a better and sustainable future technology for water security in urban and remote areas. The major issue is its low distillate productivity, which limits its widespread commercialization. In this study, the effect of silicon (Si) particles is examined to improve the absorber surface temperature of the solar still absorber plate, which is the major component for increased distillate yield. Various weight percentages of Si particles were introduced in paint and coated on the aluminum absorber surface. Extensive indoor (using a self-made halogen light-based solar simulator) and outdoor testing were conducted to optimize the concentration. The coatings with 15 wt % Si in the paint exhibited the highest increase in temperature, namely, 98.5 °C under indoor controlled conditions at 1000 W/m2 irradiation, which is 65.81% higher than a bare aluminum plate and 37.09% higher compared to a black paint-coated aluminum plate. On the other hand, coatings with 10 wt % Si reached up to 73.2 °C under uncontrolled outdoor conditions compared to 68.8 °C for the black paint-coated aluminum plate. A further increase in concentration did not improve the surface temperature, which was due to an excessive increase in thermal conductivity and high convective heat losses.

Private Housing of the Second Half of the 13th – the Beginning of the 15th Century from Archaeological Research in Kamianets-Podilskyi on Tatarska street, 17/1

The article describes the archaeological research conducted in Kamianets-Podilskyi on Tatarska Street, 17/1 in 2018. In this area, an intact archeological complex, rare for the territory of Podillya, was discovered and studied in the second half of the 13th - beginning of the 15th centuries, which corresponds to the time when these lands were part of the Golden Horde and the Grand Duchy of Lithuania. Archaeological excavations have revealed a private dwelling sunk into the mainland with a pit-cold frame-pillar structure. This housing is fundamentally different from the complex excavated in 2017 at the same time at 12 Pyatnytska Street, where the housing was a frame-pillar filled with clay. During the works, numerous materials were discovered, which made it possible for the first time to develop a typology of ceramics for the second half of the 13th - early 15th centuries for the territory of Podillya. First of all, 13 types of pots of four chronological periods were identified (the second half of the 13th - the beginning of the 14th century, the first half - the middle of the 14th century, the second half of the 14th century and the beginning - the first third of the 15th century). In turn, some types are divided into subtypes. As for the decoration of these products, their bodies were often decorated with a wavy indented line, corrugation, lines of oblique indented notches, lines of rounded indentations and painting in black paint. Jars, bowls and makitry are described separately according to morphological features. An amphora of the Lithuanian era turned out to be a valuable find. In addition, a clay ball, a denarius of Vladislav Jagail and a fragment of a metal product (chisel?) Were found during the works.

A Systematic Indoor and Outdoor Study of the Effect of Particle Size and Concentration of TiO2 in Improving Solar Absorption for Solar Still Application

Solar light absorber surface is probably one of the most important components in solar still that dictates the distillate yield. In this work, a systematic study is conducted to investigate the effect of particle size and concentration of titanium oxide (TiO2) in black paint in increasing the solar still absorber surface temperature. The various available particle sizes, i.e., 20, 150, and 400 nm, are mixed in black paint with varying concentrations and are applied on the absorber plate. XRD is used for phase identification of as-received powders. UV-Vis spectroscopy is used to examine light absorption properties. Finally, extensive indoor testing (using an improvised solar simulator) and outdoor testing are conducted to optimize the concentration. An increase in surface temperature is observed with the introduction of TiO2 nanoparticles in black paint. Furthermore, the increase in particle size leads to an increase in temperature. The highest surface temperatures of 104.86°C, 105.42°C, and 106.32°C are recorded for specimens with particles sizes 20 nm (at 15 wt% concentration), 150 nm (at 10 wt% concentration), and 400 nm (at 7 wt% concentration), respectively. Furthermore, the highest temperature of 69.69°C is recorded for TiO2-400 nm specimens under outdoor conditions, which is 15.97% higher than that of the bare aluminum plate. The increase in surface temperature may be due to high UV absorption. Moreover, an increase in particle size leads to high light-scattering ability, further improving the light-harvesting ability.

Optimization Study of Tilt Angle for Single Slope Solar Still

Water is essential to life. The origin and continuation of mankind is based on water. The supply of drinking water is an important problem for the developing countries. The wooden box has a thickness of 8mm. It consists of a top cover of transparent glass with a tilt of 18°, 26° and is coated with black paint to absorb the maximum possible solar energy. The yield of the single basin solar still is very less and it increases considerably when the solar still was built with copper sheet. An analysis of single slope solar still has done on different tilt angle to optimizing study of tilt angle. They greatly improve the rate of evaporation and the rate of condensation on the cooler surface. The efficiency is higher for solar still made up of copper sheet and its output we have got 1.24 for 18° angle. The optimized tilt angle gave more efficiency than other tilt angle. The optimize water depth is 18mm for 18° angle. This cost-effective design is expected to provide the rural communities an efficient way to convert the brackish water in to potable water.