scholarly journals EXERGY ANALYSIS OF DOUBLE-CIRCUIT FLAT SOLAR COLLECTOR WITH THERMOSYPHON CIRCULATION

2019 ◽  
Vol 9 (3) ◽  
pp. 35-39
Author(s):  
Waldemar Wójcik ◽  
Maksat Kalimoldayev ◽  
Yedilkhan Amirgaliyev ◽  
Murat Kunelbayev ◽  
Aliya Kalizhanova ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Solar Collector ◽  
Exergy Analysis ◽  
Experimental Studies ◽  
Heating System ◽  
Solar Heating ◽  
The Sun ◽  
Entire System ◽  
Exergetic Efficiency ◽  
The Difference

In the present work, an exergy analysis was done of two-circuit flat solar collector with thermosiphon circulation. The article presents a mathematical model of energy and exergic analysis of flat solar collectors, as well as calculations of solar radiation efficiency, temperature, flow rate of the fluid, exergy rates and exergy loss rates are done. The significance of the results achieved is high, since experimental studies can detect inefficient components of the solar heating system. The exergetic efficiency of a dual-circuit flat solar collector with a thermosiphon circulation describes irreversibility of the process according to thermodynamic parameters. This is caused by a large the degree of overheating achieved at the end of the processes of compression and evaporation, which leads to large differences in heat exchange temperature based on the heat pump cycle. The exergy efficiency value for the entire system is 70. Maximum values energy efficiency and exergy at noon, 32.5% and 2.23%, respectively. The efficiency of exergy is 4%, and the highest the loss of exergy is the difference between the absorber plates and the sun, accounting for 52.86% of the total exergy rate.

scholarly journals The Influence of Water and Mineral Oil On Volumetric Losses in a Hydraulic Motor

2017 ◽  
Vol 24 (s1) ◽  
pp. 213-223 ◽  
Author(s):  
Pawel Śliwiński
Keyword(s):  
Mathematical Model ◽  
Rotational Speed ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Mineral Oil ◽  
Hydraulic Motor ◽  
Small Constant ◽  
Influence Of Water ◽  
The Difference ◽  
Lubricating Properties

Abstract In this paper volumetric losses in hydraulic motor supplied with water and mineral oil (two liquids having significantly different viscosity and lubricating properties) are described and compared. The experimental tests were conducted using an innovative hydraulic satellite motor, that is dedicated to work with different liquids, including water. The sources of leaks in this motor are also characterized and described. On this basis, a mathematical model of volumetric losses and model of effective rotational speed have been developed and presented. The results of calculation of volumetric losses according to the model are compared with the results of experiment. It was found that the difference is not more than 20%. Furthermore, it has been demonstrated that this model well describes in both the volumetric losses in the motor supplied with water and oil. Experimental studies have shown that the volumetric losses in the motor supplied with water are even three times greater than the volumetric losses in the motor supplied with oil. It has been shown, that in a small constant stream of water the speed of the motor is reduced even by half in comparison of speed of motor supplied with the same stream of oil.

Design of Solar Tracker Based on Square Structure and Camera Device

2014 ◽  
Vol 672-674 ◽  
pp. 105-108
Author(s):  
Yan Liu ◽  
Jian Liu ◽  
Ying Wei Song ◽  
De Wei Zhao ◽  
Lin Zhao ◽  
...  
Keyword(s):  
Heating System ◽  
Solar Heating ◽  
The Sun ◽  
Photovoltaic Generation ◽  
Heating Systems ◽  
Solar Tracker

Solar tracker is an important part of photovoltaic generation and solar heating system. By solar tracker, the efficiency of solar utility can be significantly improved. Considering the camera device is widely applied in the photovoltaic generation and solar heating systems, based on the visual motoring equipment, a kind of solar tracker is designed. Using the proposed solar tracker, the height and the angle of the sun can be detected and be applied in solar tracker controller. Experiments show this design has relatively high accurate rate during a week’s period while the weather are partly cloudy or clear. It shows good application future in photovoltaic generation and solar heating industries.

scholarly journals Mathematical modelling of heat transfer in a greenhouse with surface soil heating system

2019 ◽  
Vol 28 (4) ◽  
pp. 569-583
Author(s):  
Volodymyr Hud ◽  
Ievgenii Gerasimov ◽  
Petro Martyniuk ◽  
Oleg Pinchuk ◽  
Pavlo Volk
Keyword(s):  
Mathematical Model ◽  
Mathematical Modelling ◽  
Surface Soil ◽  
Experimental Studies ◽  
Soil Surface ◽  
Heating System ◽  
System Structure ◽  
Soil Heating ◽  
Berry Crops ◽  
Comparison Of The Results

The use of low-temperature heat of industrial and natural origin for heating the soil in greenhouses allows practitioners to get very early vegetable and berry crops. The paper suggests a mathematical model of greenhouse heat exchange with a system of soil surface heating for substantiating the system structure and its efficiency in different conditions. The solution of the mathematical model was performed using the method of least squares in COMSOL Multiphysics software. The comparison of the results of experimental studies with the results of mathematical modelling revealed that the proposed mathematical model with a high degree of reliability allows predicting the thermal regime in greenhouses with surface soil heating using cover sleeves.

Indoor Air Temperature Analysis of Solar Heating System With Dual Heat Storage Devices

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Yu Qihui ◽  
Hao Xueqing ◽  
Tan Xin
Keyword(s):  
Mathematical Model ◽  
Air Temperature ◽  
Indoor Air ◽  
Storage Tank ◽  
Heat Storage ◽  
Heating System ◽  
Solar Heating ◽  
Minimum Size ◽  
Temperature Characteristics ◽  
Storage Devices

Using solar energy for space heating is an efficient and simply way to satisfy the energy demands of buildings. In this study, a typical office building is selected as a case model to obtain indoor air temperature characteristics with dual heat storage devices. By analyzing our solar heating system, a mathematical model of the system working process is set up. Using the software matlab/simulink for simulation, the indoor air temperature characteristics in 1 day are obtained. Simulation and experimental results show good consistency. And using the mathematical model, the storage tank size is optimized to search for the minimum size for the fixed building. Based on our analysis, the optimum ratio of storage tank A volume and collector field area is 0.11 m. This research can be a good reference for the design of the solar heating system.

scholarly journals Thermal Performance Prediction of Indoor Swimming Pool Solar Heating System Using Different Types of Flat-Plate Solar Collectors

2021 ◽  
Vol 28 (2) ◽  
pp. 08-18
Author(s):  
Laith Mohammad Haddy ◽  
Abdul-Salam D. M. Hassen
Keyword(s):  
Flat Plate ◽  
Solar Collector ◽  
Heating System ◽  
Solar Heating ◽  
Swimming Pool ◽  
Type D ◽  
Solar Fraction ◽  
Indoor Swimming Pool ◽  
Different Types ◽  
Flat Plate Solar Collector

The current study includes a theoretical study of the enfluence of different types of flat-plate solar collector on the solar fraction factor (ƒ) of a proposed solar heating system used for heating "alShaab Olympic Indoor Swimming Pool" located in Baghdad (Iraq) at a latitude of 33.32˚N. The swimming pool building has external dimensions of 95 m length, 51 m width, and 16.5 m height, it contains two pools, the first is for swimming with dimensions of (50 m * 21 m) with fixed depth of 1.8 m, the second is for diving with an irregular surface area of (351) m2 and with depth of 5 m. The Total thermal losses from the two pools to the pool hall and from the pool hall to the outdoor environment were calculated for four months of winter season (November, December, January and February) and a computer program was built using the MATLAB (R2008a) environment to solve the mathematical model equations in order to calculate the solar fraction facor (ƒ) of the proposed solar heating system at different solar collecting areas which are (2000,2500,3000,3500,4000,4500,5000,6000,7000,8000,9000,10000) m2 and at five different types of flat-plate solar collector which are (A: one cover black solar collector, B: one cover selective absorber solar collector, C: two cover black solar collector, D: two cover selective absorber solar collector, and E: pool absorber (PVC) solar collector). The results obtained showed that the highest values of solar fraction factor were obtained when using the solar collector type D, and the lowest values obtained when using the solar collector type E. The values of solar fraction factor (ƒ) of the proposed solar heating system, at solar collecting area of 10000m2 and at mass storage of water in the storage tank of 25 kg/m2 collecting area, for type D are 84.27 % for November, 72.74% for December, 69.4% for January, and 82.91% for February, and for type E are 56.14% for November, 41.15% for December, 37.17% for January, and 50.6% for February.

The Design of Solar Heating System Used in Oilfield

2012 ◽  
Vol 461 ◽  
pp. 389-392
Author(s):  
Peng Min Dong ◽  
Bo Zhao ◽  
Zong Liang Zhu ◽  
Yong Dong Qiang ◽  
Zhi Gang Yao ◽  
...  
Keyword(s):  
Solar Collector ◽  
Heating System ◽  
Great Emphasis ◽  
Solar Heating ◽  
Electrical Heating ◽  
Water Tank ◽  
Severe Condition ◽  
Expected Effect ◽  
Auxiliary Power ◽  
Pipeline Design

Based on the natural environment of YuMen oilfield, we designed solar collector and auxiliary power heating system. We lay great emphasis on the area of the collector , auxiliary electrical heating power,the volume of water tank and pipeline design in this system. After being used, this system warmth achieves the expected effect and meets the requirement of heating in severe condition such as Yumen in china.

scholarly journals Mass flow rate optimization in solar heating systems based on a flat-plate solar collector: A case study

2021 ◽  
Vol 12 (3) ◽  
pp. 061-071
Author(s):  
Samer Yassin Alsadi ◽  
Tareq Foqha
Keyword(s):  
Flat Plate ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Solar Collector ◽  
Optimization Problems ◽  
Heating System ◽  
Solar Heating ◽  
Outlet Temperature ◽  
Solar Systems

Little works considered the optimization of working fluids in solar systems. Engineers, designers and scientists are interested with the optimization problems, furthermore it is very important specially, for solar systems to improve the energetic behavior and increase their efficiencies as a conversion system of solar irradiance to a useful thermal power. According to the available literature, the criteria of optimization mainly relates to energetic and economic analysis (one of them or both). The analysis was based upon the maximum useful energy obtained from solar collector. Accordingly, the optimum mass flow rate was found aspires to infinity. The second analysis is based upon minimum cost of the unit of useful energy [$/W]. The optimum mass flow rate of solar air-heating flat-plate collector for the considered domestic solar heating system has been found 29 kg/h per square meters of solar collectors. This paper deals with a third criteria that is, the amount of the additional energy required to achieve the required task from the solar system by means of auxiliary heating system. In where both the outlet temperature and mass flow rate play crucial role in the heat exchange between the fluid in the collector loop and the fluid in the load loop.

Numerical Study of the Acoustic Efficiency of Sound-Absorbing Structures with Resonators of Various Forms

2018 ◽  
Vol 931 ◽  
pp. 158-163 ◽  
Author(s):  
Pavel V. Pisarev ◽  
Aleksandr N. Anoshkin ◽  
Karina A. Maksimova
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Numerical Solution ◽  
Numerical Experiments ◽  
Numerical Study ◽  
Experimental Studies ◽  
Acoustic Properties ◽  
Acoustic Characteristics ◽  
The Difference ◽  
Comparison Of The Results

The present work is devoted to a numerical study of the acoustic characteristics of cubic and folded resonators of sound-absorbing structures (SAS). In the process of work, a physical statement of the problem and a mathematical model for predicting the effective acoustic properties of the SAS cells are formulated. The validation of the developed mathematical models was carried out. During the comparison of the results of a numerical solution with experimental studies, the difference did not exceed 3%. Based on the results of the numerical experiments, the most effective resonators were identified, and recommendations on the design of the SAS on their basis were formulated.

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