The Study on Heating Running Schemes of Solar Energy Combined with Municipal Heating

2013 ◽  
Vol 790 ◽  
pp. 160-164
Author(s):  
Yong An Ao ◽  
Gang Li ◽  
Wei Xin Kong ◽  
Qi Feng
Keyword(s):  
Mathematical Model ◽  
Solar Energy ◽  
Water Temperature ◽  
Solar Collector ◽  
Heat Load ◽  
Environmental Benefits ◽  
Combination System ◽  
Save Energy ◽  
The Mathematical Model ◽  
Heat Amount

The research, based on combination system of solar energy and municipal heating network, studied the running scheme of combination system of solar energy and municipal heating network through ways of experiments and theoretical calculation of the mathematical model. Firstly, the research established mathematical model of heat equilibrium of the combination system of solar energy and municipal heating network; secondly, keeping the indoor heat load steady, compared the dynamic heat load provided by solar collector with that needed by heated room at the same time,determined time spans of the network stopping service and the heat load added by the network within 24 h. In the research we took a heating period in a typical room in Shenyang for example, under the conditions of low temperature floor radiant with heating index standard of 50W/ m2 and 50°C of the average supplied water temperature, 40 °C of the return water temperature, calculated and verified the established mathematical model. The results include: when the heat load provided by solar collector is greater or less than the heat needed by the room, how many heat amount should be supplied by the running network and the amount of water flow within the network pipes correspondingly, and how long the network runs or stops. The final conclusions include: whether the running scheme of the combination system can save energy? the conditions of energy saving in running a combination system, and whether the system can bring environmental benefits.

The Design on Heating System for Experiment of Solar Energy and Geothermal-Source Heat Pump

2012 ◽  
Vol 512-515 ◽  
pp. 194-197
Author(s):  
Ying Ling Cai ◽  
Yin Long Wu ◽  
Hua Zhang ◽  
Ji Wei Li
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Solar Energy ◽  
Heat Pump ◽  
Dynamic Load ◽  
Solar Collector ◽  
Heating System ◽  
Solar Collectors ◽  
Heating Load ◽  
The Mathematical Model

Through the study on the project, we can easily find that if we do not need heat the whole day, adopting the dynamic load method to calculate the heating load is more advisable compared to adopting a steady-state one, especially when we select the equipment. After establishing the mathematical model of the project, under the premise of meeting the heating load, considered the economy, the optimal solar collector area of this project is 11.1 square meters. In addition, through simulating the project, we can learn that the best azimuth of solar collectors in Shanghai is south by east 22.5 °.

scholarly journals Development of condenser mathematical model for research and development of ways to improve its efficiency

2020 ◽  
Vol 18 (4) ◽  
pp. 578-585
Author(s):  
Madina Shavdinova ◽  
Konstantin Aronson ◽  
Nina Borissova
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Water Temperature ◽  
Steam Turbine ◽  
Cooling Water ◽  
Laboratory Research ◽  
Thermal Engineering ◽  
Linear Regression Method ◽  
Cooling Water Temperature ◽  
The Mathematical Model

The condensing unit is one of the most important elements of the steam turbine of a combined heat and power plant. Defects in elements of the condensing unit lead to disturbances in the steam turbine operation, its failures and breakdowns, as well as efficiency losses of the plant. Therefore, the operating personnel need to know the cause of the malfunction and to correct it immediately. There are no diagnostic models of condensers in the Republic of Kazakhstan at the moment. In this regard, a mathematical model of a condenser based on the methodology of Kaluga Turbine Plant (KTP) has been developed. The mathematical model makes it possible to change the input parameters, plot dependency diagrams, and calculate the plant efficiency indicators. The mathematical model of the condenser can be used to research ways for the improvement of the condensing unit efficiency, for diagnostic purposes of the equipment condition, for the energy audit conduction of the plant, and in the training when performing virtual laboratory research. Using static data processing by linear regression method we obtain that the KTP methodology of condenser calculation is fair at cooling water temperature from 20 °C to 24 °C, but at cooling water temperature from 20 °C to 28 °C, the methodology of JSC "All-Russia Thermal Engineering Institute" (JSC "VTI") is used. One of the ways to increase the condenser efficiency has been proposed. It is the heat transfer augmentation with riffling annular grooves on tubes. This method increases the heat transfer coefficient by 2%, reduces the water subcooling of the heating steam by 0.9 °C, and decreases the cooling area by 2%.

scholarly journals Numerical simulation of concentrating solar collector P2CC with a small concentrating ratio

2012 ◽  
Vol 16 (suppl. 2) ◽  
pp. 471-482 ◽  
Author(s):  
Velimir Stefanovic ◽  
Sasa Pavlovic ◽  
Marko Ilic ◽  
Nenad Apostolovic ◽  
Dragan Kustrimovic
Keyword(s):  
Mathematical Model ◽  
Fluid Flow ◽  
Solar Radiation ◽  
Solar Energy ◽  
Radiation Intensity ◽  
Solar Collector ◽  
Numerical Procedure ◽  
Working Fluid ◽  
Flow Rates ◽  
Solar Radiation Intensity

Solar energy may be practically utilized directly through transformation into heat, electrical or chemical energy. A physical and mathematical model is presented, as well as a numerical procedure for predicting thermal performances of the P2CC solar concentrator. The demonstrated prototype has the reception angle of 110? at concentration ratio CR = 1.38, with the significant reception of diffuse radiation. The solar collector P2CC is designed for the area of middle temperature conversion of solar radiation into heat. The working fluid is water with laminar flow through a copper pipe surrounded by an evacuated glass layer. Based on the physical model, a mathematical model is introduced, which consists of energy balance equations for four collector components. In this paper, water temperatures in flow directions are numerically predicted, as well as temperatures of relevant P2CC collector components for various values of input temperatures and mass flow rates of the working fluid, and also for various values of direct sunlight radiation and for different collector lengths. The device which is used to transform solar energy to heat is referred to as solar collector. This paper gives numerical estimated changes of temperature in the direction of fluid flow for different flow rates, different solar radiation intensity and different inlet fluid temperatures. The increase in fluid flow reduces output temperature, while the increase in solar radiation intensity and inlet water temperature increases output temperature of water. Furthermore, the dependence on fluid output temperature is determined, along with the current efficiency by the number of nodes in the numerical calculation.

Mathematical Model of Oceanographic Buoy Solar Energy Power Source Design Based on Double Batteries

2013 ◽  
Vol 740 ◽  
pp. 782-786
Author(s):  
Guo Liang Zou ◽  
Xin Nan Lou
Keyword(s):  
Mathematical Model ◽  
Solar Energy ◽  
Power Supply System ◽  
Supply And Demand ◽  
Power Source ◽  
Supply System ◽  
Rainy Weather ◽  
The Mathematical Model ◽  
Engineering Projects ◽  
Rainy Days

To implement the objective of steady operation of the marine observation buoy system on the sea throughout the year,based on energy balance between supply and demand, this paper presents the mathematical model of solar energy power supply system derived from double batteries switching technology. The batteries are divided into main batteries and auxiliary batteries. The main batteries are used regularly and the auxiliary batteries are used in periodic rainy weather. The main advantage of this model is that the capacity of auxiliary batteries can be dynamic calculated based on the numbers of maximum continuous rainy days and minimum intervals between rainy days. The batteries capacity is sufficient but not redundant. This design project has been tested on marine buoy and the accuracy of the model is splendid for most engineering projects.

On the Characteristics of a Novel Floating Sub-Atmospheric Solar Water Desalination System

2011 ◽  
Vol 110-116 ◽  
pp. 2139-2147
Author(s):  
Hooman Mohammad Pour ◽  
Mehdi Ashjaee
Keyword(s):  
Mathematical Model ◽  
Solar Radiation ◽  
Water Temperature ◽  
Water Resource ◽  
Atmospheric Condition ◽  
Water Desalination ◽  
Incident Solar Radiation ◽  
Solar Water ◽  
Significant Parameter ◽  
The Mathematical Model

This paper proposes a new floating sub-atmospheric solar water desalination system to provide the water resource for domestic to industrial usage. In addition to conventional solar stills (CSS) which only utilize incident solar radiation, the sub-atmospheric condition of this system greatly increases the productivity of the system. The mathematical model of the system is developed and the performance of the still is evaluated. The overall productivity of the still is shown to be sensitive to evaporator pressure as the most significant parameter of the system. Other parameters affecting the performance include cover transmissivity and input water temperature.

scholarly journals Mathematical Model of the Controlled Object when Regulating the Working Volume of the Manipulator Pump

2018 ◽  
Vol 7 (4.36) ◽  
pp. 1058
Author(s):  
Bulat F. Bairamov ◽  
Artur A. Fardeev ◽  
Albert R. Fardeev
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Hot Stamping ◽  
Automated System ◽  
Working Zone ◽  
Working Volume ◽  
Useful Power ◽  
Save Energy ◽  
The Mathematical Model ◽  
Controlled Object

This paper describes the constructed mathematical model of the controlled object of the automated system for controlling the displacement volume of the manipulator pump. The change in pump displacement volume is performed in order to save energy by minimizing the fluid drain through the overflow valve. The use of the considered manipulator is intended in the process of automated supply of blanks to the working area of a press used in forging and hot stamping processes. The reactive forces acting on the moving parts of the mobility modules from the fixed parts of the manipulator are determined. Conversion of the useful power of the pump into the useful power of hydraulic motors is performed. This takes into account the losses using efficiency. An equation describing the mathematical model of the controlled object is obtained. This equation is represented in relative variables. The derivation of this equation and the determination of the reactive forces are made on the basis of the assumption that all transport degrees of freedom are translational. This limitation is caused by the peculiarities of the working area of the press used in technological processes of forging and hot forming of blanks. The working zone is a deep horizontal tunnel, the movement of the working object in which is possible only with translational degrees of freedom.  

scholarly journals Study of Air Flow in A Solar Collector Equipped with Two Inclined Obstacles

2021 ◽  
Vol 321 ◽  
pp. 04015
Author(s):  
Fayssal Benosman ◽  
Mohammed Amine Amraoui
Keyword(s):  
Mathematical Model ◽  
Reynolds Number ◽  
Solar Collector ◽  
Air Flow ◽  
Solar Air Collector ◽  
The Mathematical Model ◽  
Calculation Code

In the present work we have studied the case of a conventional solar air collector and try to see how is it possible to improve it-s efficiency, by changing Reynolds number. Given the complexity of the problem we used the FLUENT calculation code. We made the mathematical model, then we gave a validation of our result by the results of Dimartini, we gave fields of speed, turbulence and a Nusselt profile and factor of friction as a function of the Reynolds Number. The results show that variation of Reynolds number has an influence on the performance of the solar collector, which is why we have used several values in order to observe the most suitable one.

scholarly journals Procedure for the quantification of the degradation index of Photovoltaic Generators

2021 ◽  
Vol 2 (2) ◽  
pp. 47-53
Author(s):  
Proenza Y. Roger ◽  
Camejo C. José Emilio ◽  
Ramos H. Rubén
Keyword(s):  
Mathematical Model ◽  
Power Generation ◽  
Solar Energy ◽  
Operating Conditions ◽  
Energy Research ◽  
Degradation Index ◽  
Starting Point ◽  
Santiago De Cuba ◽  
Photovoltaic Generators ◽  
The Mathematical Model

A procedure is presented for the quantification of the degradation index of Photovoltaic Generators, based on the quantification of the operational losses inherent in the system, which allows maintaining the nominal operating conditions and by the warranty terms of the photovoltaic generator. A photovoltaic generator connected to the network with a nominal power of 7.5 kWp, installed in the Solar Energy Research Center of Santiago de Cuba, is used to evaluate and validate the procedure. The starting point is the mathematical model of the photovoltaic generator, then the operational losses of the photovoltaic generator are quantified and the mathematical model is adjusted to real conditions, through a polynomial adjustment.  The results obtained show that the photovoltaic generator presents deviations in terms of the nominal power generation, because the operational losses are 7% with respect to the values ​​given by the manufacturer.

scholarly journals Fault Diagnostic Methodology for Grid-Connected Photovoltaic Systems

2021 ◽  
Vol 2 (2) ◽  
pp. 10-30
Author(s):  
Proenza Y. Roger ◽  
Camejo C. José Emilio ◽  
Ramos H. Rubén
Keyword(s):  
Mathematical Model ◽  
Fault Diagnosis ◽  
Solar Energy ◽  
False Alarm ◽  
False Alarm Rate ◽  
Real System ◽  
Photovoltaic Systems ◽  
Energy Research ◽  
Santiago De Cuba ◽  
The Mathematical Model

This research focuses on the design of a fault diagnosis methodology to contribute to the improvement of efficiency, maintainability and availability indicators of Grid-Connected Photovoltaic Systems. To achieve this, we start from the study of the mathematical model of the photovoltaic generator, then, a procedure is performed to quantify the operational losses of the photovoltaic generator and adjust the mathematical model of this to the real conditions of the system, through a polynomial adjustment. A real system of nominal power 7.5 kWp installed in the Solar Energy Research Center of the province of Santiago de Cuba is used to evaluate the proposed methodology. Based on the results obtained, the proposed approach is validated to demonstrate that it successfully supervises the system. The methodology was able to detect and identify 100% of the simulated failures and the tests carried out had a maximum false alarm rate of 0.22%, evidencing its capacity.

Numerical Modeling of Wet Cooling Towers—Part 1: Mathematical and Physical Models

1983 ◽  
Vol 105 (4) ◽  
pp. 728-735 ◽  
Author(s):  
A. K. Majumdar ◽  
A. K. Singhal ◽  
D. B. Spalding
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Water Temperature ◽  
Heat And Mass Transfer ◽  
Computer Code ◽  
Hot Water ◽  
Physical Models ◽  
Cooling Towers ◽  
Transfer Rates ◽  
The Mathematical Model

The paper discusses the limitations of current practices of evaluating thermal performance of wet cooling towers and describes a more advanced mathematical model for mechanical and natural draft cooling towers. The mathematical model computes the two-dimensional distributions of: air velocity (two components); temperature, pressure, and moisture content; and water temperature. The downward direction of water flow is presumed. The local interphase heat and mass transfer rates are calculated from empirical correlations for which two options are provided. In the first option, only one constant (Ka, based on Merkel’s approximations) is employed; in the second option, two separate constants for heat and mass transfer are used. Boundary conditions can be either of the prescribed cooling range or of the prescribed hot water temperature types. The governing equations are solved by a finite difference method. The model is embodied into a computer code (VERA2D) which is applicable for the natural and mechanical draft towers of both the crossflow and counterflow arrangements. Several applications of the code are described in Part II of the paper.

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