Improving the Potable Water from Tubular Solar Still Using Eggshell Powder as an Natural Energy Storage Medium - An Experimental Approach

It seems like every hour, there is a greater need for fresh water. The demand for fresh water is rapidly growing as a consequence of the expanding population and the increased urbanization of the world's population. The tubular solar still offers much larger evaporative and condensing surface areas than normal single slope solar still. The scope of this study is to improve the performance of tubular solar still by employing eggshells as the bed material, which has good heat absorption properties. Results showed that the influence of eggshell powder as energy storage material in the basin improved the average water temperature by 10.8, 10.9, and 8.73% for the water thickness of 10, 15, and 20 mm respectively. The usage of eggshells as an energy store in the basin results in an increase of about 60.77 % potable water produced. The maximum observed distillate output from the solar still is 0.6 kg for solar stills with eggshell powder as energy storage material and 0.34 kg for solar stills without eggshell powder in the absorber of TSS at peak solar radiation and at the lowest water thickness of 10 mm. The hourly potable water generated from TSS using eggshell as an energy storage material increased by roughly 47% compared to the flat absorber without eggshell powder. TSS with eggshell powder as energy storage has a daily energy efficiency of 79.19, 75.49, and 44.18 % for water thicknesses of 10, 15, and 20 mm in the basin. Tubular solar still using eggshell as energy storage material and tubular solar still without any material produced 3.62 kg and 1.42 kg average yields at a water thickness of 10 mm. Water thickness of 10, 15, and 20 mm has performance improvement ratios of 2.54, 2.51, and 2.18 respectively.

Hydrothermal Regime Variation and Ecological Effects on Fish Reproduction in the Yangtze River

Water temperature, as one of the important water environment impact factors, has a significant impact on the survival and development of aquatic organisms. We selected water temperature data (1959–2017) from four key hydrological stations in the Yangtze River: Cuntan, Yichang, Hankou, and Datong. We analyzed the characteristics and variability of the Yangtze River hydrothermal regime by the Mann-Kendall method, wavelet analysis, and by the IHA-RVA method to analyze hydrothermal regime variations of the Yangtze River, and the response mechanisms of fish to variations in hydrothermal regimes were explored. The results show that (1) The annual average water temperature of the Yangtze River is warming, and Cuntan Station, Yichang Station, Hankou Station, and Datong Station have a sudden increase in temperature in 2002, 1995, 2003, and 2004, and the periodicity analysis demonstrates that Cuntan, Yichang, and Datong stations all have main periods of 24~32 years; (2) The overall variations of 32 hydrothermal indicators at Cuntan Station and Yichang Station reached 65% and 61%, which are close to the height variation; (3) With the construction of the Three Gorges Dam, the stagnant cooling effect caused the arrival date of the upper reproduction water temperature of “The four major fish species” to be delayed by about 23 days, and the stagnant heat effect caused the arrival date of the Chinese sturgeon reproduction upper limit water temperature to be delayed by about 30 days.

Seasonal Variations In Species Composition And Community Structure In The Eastern Coast of South Korea

The seasonal variations in species composition of set net fisheries were investigated in the eastern coast of Korea, from 2007 to 2008. In total, 51 species were found that were classified into 15 orders and 33 families. The water temperature of the study area was 0.1–2.1 °C during the study period, which was higher than the average water temperature in the last decade. Monthly variation in the number of species peaked twice, in May (spring) and November (autumn) when the water temperature increased and decreased, respectively, and monthly variation in the number of individuals showed a remarkably high trend in winter and autumn and was mainly caused by large migratory species. Based on the cluster analysis of the 18 most dominant species with more than 0.4% of the total number of individuals, we divided the species composition and community structure into three groups: fishes with temporary appearance (Group A), fishes with long-term appearance (Group B), and dominant pelagic fishes appearing with long-term appearance (Group C). We could conclude that seasonal variation in the fish community structure was mainly caused by pelagic migration of species under high water temperature conditions during the study period.

Layer-Averaged Water Temperature Sensing in a Lake by Acoustic Tomography with a Focus on the Inversion Stratification Mechanism

Continuous sensing of water parameters is of great importance to fluid dynamic progress study in oceans, coastal areas and inland waters. The acoustic tomography technique can perform water temperature field measurements horizontally and vertically using sound wave travel information. The layer-averaged water temperature can also be measured with the acoustic tomography method. However, investigations focusing on the stratified mechanism, which consists of stratification form and its influence on inversion error, are seldom performed. In this study, an acoustic tomography experiment was carried out in a reservoir along two vertical slices to observe the layer-averaged water temperature. Specifically, multi-path sound travel information is identified through ray tracing using high-precision topography data obtained via a ship-mounted ADCP during the experiment. Vertical slices between sound stations are divided into different layers to study layer division inversion methods in different preset types. The inversion method is used to calculate the average water temperature and inversion temperature error of every layer. Different layer methods are studied with a comparison of results. The layer division principle studied in this paper can be used for layer-averaged water temperature sensing with multi-path sound transmission information.

Assessment of Physico-chemical Properties of Different Water Reservoirs of Barishal City, Bangladesh

There are many man-made water reservoirs found in Barishal City. This study was aimed to assess the existing condition of physico-chemical properties of four different water reservoirs, namely Bibir Pukur (pond), Amtala Lake, Choumatha Lake and City Corporation Pond of Barishal City of Bangladesh. To evaluate the physico-chemical properties, the average of the parameters such as water temperature, total dissolved solids, electric conductivity (EC), pH, salinity, as well as depth, color, and transparency of water were analyzed. The highest average water temperature was found in the City Corporation Pond, which determined as 31.77±0.09 °C. Electric conductivity (ms/cm) and total dissolved solids (ppm) of Amtala Lake were 0.413 ±0.009 and 199±1.15. The highest average pH 7.88±0.01 and lowest salinity 140±1.73 were found in City Corporation Pond and Choumatha Lake respectively. The water depth of Bibir Pukur was 260.33± 13.98 cm which is the highest among the four water reservoirs. The highest values of dissolved oxygen and phosphate were 2.03±0.12 mg/l and 294.12±3.92 μg/l.

THE EFFECT OF PLATE GEOMETRY OF FLAT PLATE SOLAR COLLECTOR UNDER VARIABLE HEAT FLUX

In the current study, the effect of different plate geometry namely smooth plate (traditional model) and V-corrugated plate (new model) on the output of the FPSC is conducted numerically and experimentally. The outdoor experimental work has been done in Baghdad- Iraq. All geometric models and the numerical simulations were carried out in the current study using the commercial CFD method, ANSYS 19. R3. The results indicated that the difference between numerical results and experimental findings is 8.12 % for average water temperature in a tank, while the working fluid temperature at the exist of riser pipe is about 8.36 %. The thermal performance for the new model is found higher than that for traditional model. The thermal performance of new model in terms of water temperature inside the tank was found higher than traditional model by 10.7 %. In addition, the overall thermal efficiency of collector for the new model has been increased about 9.9 % than traditional model.

An Experimental Study on Operating Characteristic of Radiant Floor Cooling Integrated with Underfloor Ventilation System

In this paper, an experimental study on radiant floor cooling integrated with underfloor ventilation (RFCUV) system was conducted. Indoor environment temperatures, radiant floor cooling system parameters and underfloor ventilation system parameters were measured. Humane thermal comfort was analyzed experimentally. And the effects of disturbance variables and manipulated variables on controlled variables were analyzed. The results illustrated that operative temperature (OT), predicted mean vote (PMV) and predicted percent dissatisfied (PPD) decrease in the first two hours and then become stable in ISO7730 recommended value range. IAT and OT increase with the increasing of the disturbance variables and manipulated variables. The increasing ratio of indoor air temperature (IAT) and OT are relatively small when comprehensive outdoor air temperature is relatively high and indoor heat quantity or average water temperature is relatively low. IAT and OT increase approximately linearly with the increasing of supply air temperature.

THE EFFECT OF CLIMATE CHANGE ON THE THERMAL REGIME IN THE RYBINSK RESERVOIR

According to the data of the Rybinsk Hydrometeorological Observatory (HMO) and archival data of the Laboratory of Hydrology, Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, the seasonal variability of the main climate parameters, air temperature (Rybinsk HMO) and water temperature in the Rybinsk Reservoir have been studied at the modern stage of global warming (2001–2019). Over the period of 1976–2019, the rate of an increase in the average annual air temperature was 0.50°C /10 years in the littoral zone of the Rybinsk Reservoir. Changes in the timing of the onset and end of the climatic seasons of the year and an increase in their duration have been determined. It is found that during the modern period the average surface air temperature was higher than the climatic norm in all months of the year (1960–1990). During the growing season (conventionally May–October), its maximum increase was recorded in July, 1.5°C, May and September, 1.2°C. It is shown during the modern period of intensive global warming the average decadal water temperature in the spring, summer, and autumn seasons increased compared to the norm. The maximum positive anomalies were recorded in the second-third decade of May, 2.8–2.3°C and July, 2.0°C. According to observations at the standard stations, significant differences were recorded in water mass heating: in July in anomalously warm summer of 2010 the average water temperature was 27°C in the surface layer and 18.5°C in the near bottom layer; in the cold summer of 2017, the temperature was 18.5 and 16.0°C, respectively. The monitoring data on the water temperature in the reservoir indicate an increase in the number of years with anomalous thermal conditions as a result of climate change. The earlier temperature stratification of water masses (the end of May) and decrease in the difference in the temperature between the surface and near-bottom water layers have been observed.

Comfort of Domestic Water in Residential Buildings: Flow, Temperature and Energy in Draw-Off Points: Field Study in Two Danish Detached Houses

There is very little knowledge on the occupant actual hot water comfort (temperature and flow), usage practice, and routines (temporal and spatial distribution of hot water usage in a household). This paper describes the results from the total and hot water measurements in two Danish detached houses. The results show that, at the draw-off points, the temperature of 55 °C is never asked by the occupants, not even in the kitchen sink. The domestic water temperature differentiates depending on the function of the draw-off point, with the shower and kitchen taps being most energy- and water-intense. They constitute around 90% of the hot water use in the house. Shower units on average demand for highest temperature (i.e., 35.5 °C to 40.4 °C). Hand washing operates, on average, at temperature between 20.5 °C to 26.5 °C. Average water temperature at the taps located in utility room varies between 23 °C to 26 °C. These in-depth insight in the total and hot water use in two new-built low energy houses, can a) help building professionals designing more efficient hot water installations; b) enhance the research work on energy flexibility buildings by providing knowledge on most energy-intensive draw-off points; and c) facilitate district heating professionals in improving the network performance.

Daily, seasonal, and annual variability of temperature in streams inhabited by the endemic San Pedro Martir trout (Oncorhynchus mykiss nelsoni), in Baja California, Mexico, and the predicted temperature for the years 2025 and 2050

The present study measured the daily, seasonal, and annual variability of the water temperature of streams in which the endemic rainbow trout, Oncorhynchus mykiss nelsoni, is distributed on the western slope of the Sierra San Pedro Mártir, Baja California, Mexico, between 1996 and 2019. The seasonal thermal interval and daily duration of summer temperatures above the thermal threshold for this trout subspecies (≥ 28°C) were determined in streams at different elevations (553, 1,220, and 2,080 masl, or meters above sea level). Temperatures ≥ 28°C were recorded at the study site on the stream with the lowest elevation (San Antonio de Murillos Creek) over an accumulated 365 h between June and September 2014, with the maximum temperature recorded there, 30.66 °C, making it the site most vulnerable to climate change. At the San Antonio de Murillos Creek, the average water temperature predicted by three models (GFDL R30, HadCM3, and Mote) for the year 2025 would be a non-lethal temperature, < 28 °C, for trout at a minimum elevation of 491-511 masl, while this was predicted to be 545-701 masl for the year 2050. Predicted hourly water temperatures of 28°C (non-lethal) may occur at minimum elevations of 868-898 masl in 2025 and at 908-1028 masl in 2050, reducing a 21-23% and 23-31% its current altitudinal distribution range, respectively, thus avoiding its presence at the type locality (San Antonio de Murillos).