scholarly journals Experimental Evaluation of Double Air Pass Solar Collector in Humid Tropical Environment

2020 ◽  
pp. 23-29
Author(s):  
Kwamegni Seunou Kreis Vermeil ◽  
Tetang Fokone Abraham ◽  
Edoun Marcel ◽  
Kuitche Alexis ◽  
Ghiaus Adrian- Gabriel
Keyword(s):  
Solar Radiation ◽  
Solar Collector ◽  
Flow Direction ◽  
Experimental Tests ◽  
Weather Conditions ◽  
Heat Transfer Fluid ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Outlet Temperature ◽  
The University

The present work was focused on the experimental investigation of a double air pass solar collector which was designed and constructed at the Laboratory of Energetic and Thermal Applied of the National School of Agro-Industrial Sciences of the University of Ngaoundere. It consists of a double glazed cover with a surface of 0.47 m², an absorbent plate and a layer of thermal insulation. It allows simultaneous circulation and the same flow direction of the working fluid (air) on both side of the absorber. The experimental tests were conducted outdoor, in natural environment of Ngaoundéré city, during one month period, from 4 to 30 of April, between 9:00 am and 5:00 pm, local time. The research aim was to characterize, on one hand, the local weather conditions (solar radiation, ambient temperature, relative humidity and wind velocity), and on the other hand the collector performance. The solar collector was permanently oriented towards the South and tilted by 45° with respect to the horizontal plane. The analysis of the temperature profiles of different components  of the collector showed that the maximum temperature was reached at 2:30 pm, when solar radiation was 1217 W/m² and they were 73.9°C, 61.7°C and 44.7°C for absorber, inner glass  and outer glass, respectively. As concerning the outlet temperature of the heat transfer fluid, the analysis of the results shows that it goes up to 58.4°C and 52.2°C, while thermal efficiency was as high as 47.81% and 65.57% when the air flow velocities were setup at 0.5 m/s and 1.5 m/s, respectively.

A 3-D Model Simulation of High Temperature Solar Cavity Receiver

2017 ◽  
Author(s):  
Huayi Feng ◽  
Yanping Zhang ◽  
Chongzhe Zou
Keyword(s):  
Heat Transfer ◽  
Radiation Intensity ◽  
Large Scale ◽  
Model Simulation ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Outlet Temperature ◽  
Fluid Temperature ◽  
Heat Transfer Efficiency ◽  
Direct Normal Irradiance

In this paper, a 3-D numerical model is proposed to investigate the capability of generating high operating temperature for a modified solar cavity receiver in large-scale dish Stirling system. The proposed model aims to evaluate the influence of radiation intensity on the cavity receiver performance. The properties of the heat transfer fluid in the pipe and heat transfer losses of the receiver are investigated by varying the direct normal irradiance from 400W/m2 to 1000W/m2. The temperature of heat transfer fluid, as well as the effect of radiation intensity on the heat transfer losses have been critically presented and discussed. The simulation results reveal that the heat transfer fluid temperature and thermal efficiency of the receiver are significantly influenced by different radiation flux. With the increase of radiation intensity, the efficiency of the receiver will firstly increase, then drops after reaching the highest point. The outlet working fluid temperature of the pipe will be increased consistently. The results of the simulations show that the designed cylindrical receiver used in dish Stirling system is capable to achieve the targeted outlet temperature and heat transfer efficiency, with an acceptable pressure drop.

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.

scholarly journals Study of Affecting Factors of Meteorological Parameters on Solar Radiation in Kathmandu Valley

The Batuk ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 72-80
Author(s):  
Prakash M. Shrestha ◽  
Khem N. Poudyal ◽  
Narayan P. Chapagain ◽  
Indra B. Karki
Keyword(s):  
Solar Radiation ◽  
Meteorological Parameters ◽  
Weather Conditions ◽  
Global Solar Radiation ◽  
Solar Irradiation ◽  
Maximum Temperature ◽  
Affecting Factors ◽  
Air Mass ◽  
High Level ◽  
Relative Sunshine

Solar radiation data are great significance for solar energy systems. This study aimed to estimate monthly and seasonal average daily global solar radiation on a horizontal surface in Kathmandu (27.7oN, 85.5oE, 1350 masl), Nepal, by using CMP6 pyranometer in 2012. The influence of the global solar irradiation from different physical as well as meteorological parameters was analyzed. Besides this, the research highlighted that there is high level of fluctuation of the measured value of global solar irradiance due to local weather conditions. As a result of this measurement, the maximum, minimum monthly and yearly mean solar radiation values were (21.32 ± 4.14) MJ/m2/day in May,(10.93 ± 2.03) MJ/m2/day in January and (16.68 ± 4.60)MJ/m2/day found respectively. Annual average of clearness index, maximum temperature, minimum temperature, relative sunshine hour, air mass are 0.51 ± 0.12, (26.23 ± 4.96)oC, (12.38 ± 6.83)oC, 0.57 ± 0.165 and 1.54 ± 0.42 respectively. There is positive correlation of maximum temperature and negative correlation of air mass with global solar radiation.

scholarly journals Experimental and Techno-Economic Analysis of Solar-Geothermal Organic Rankine Cycle Technology for Power Generation in Nepal

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Suresh Baral
Keyword(s):  
Power Generation ◽  
Heat Source ◽  
Power Output ◽  
Solar Collector ◽  
Hot Spring ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Working Fluids

The current research study focuses on the feasibility of stand-alone hybrid solar-geothermal organic Rankine cycle (ORC) technology for power generation from hot springs of Bhurung Tatopani, Myagdi, Nepal. For the study, the temperature of the hot spring was measured on the particular site of the heat source of the hot spring. The measured temperature could be used for operating the ORC system. Temperature of hot spring can also further be increased by adopting the solar collector for rising the temperature. This hybrid type of the system can have a high-temperature heat source which could power more energy from ORC technology. There are various types of organic working fluids available on the market, but R134a and R245fa are environmentally friendly and have low global warming potential candidates. The thermodynamic models have been developed for predicting the performance analysis of the system. The input parameter for the model is the temperature which was measured experimentally. The maximum temperature of the hot spring was found to be 69.7°C. Expander power output, thermal efficiency, heat of evaporation, solar collector area, and hybrid solar ORC system power output and efficiency are the outputs from the developed model. From the simulation, it was found that 1 kg/s of working fluid could produce 17.5 kW and 22.5 kW power output for R134a and R245fa, respectively, when the geothermal source temperature was around 70°C. Later when the hot spring was heated with a solar collector, the power output produced were 25 kW and 30 kW for R134a and R245fa, respectively, when the heat source was 99°C. The study also further determines the cost of electricity generation for the system with working fluids R134a and R245fa to be $0.17/kWh and $0.14/kWh, respectively. The levelised cost of the electricity (LCOE) was $0.38/kWh in order to be highly feasible investment. The payback period for such hybrid system was found to have 7.5 years and 10.5 years for R245fa and R134a, respectively.

Thermochemical Conversion of Biomass Using Solar Energy: Use of Nanoparticle-Laden Molten Salt as the Working Fluid

2009 ◽  
Author(s):  
Himanshu Tyagi ◽  
Patrick E. Phelan ◽  
Ravi S. Prasher
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Molten Salt ◽  
Concentration Factor ◽  
Solar Collector ◽  
Energy Use ◽  
Operating Conditions ◽  
Thermochemical Conversion ◽  
Working Fluid ◽  
Fluid Mixture

Solar energy can potentially be used to convert biomass into more readily usable fuel. The use of solar energy in such a process improves the overall conversion efficiency of the system significantly by eliminating combustion of a portion of biomass needed to heat the rest of it to a temperature where pyrolysis occurs. The present study models the thermochemical conversion process during pyrolysis of biomass matter into product gases. Concentrated solar radiation is used as the source of heating of the biomass. The biomass is indirectly heated by a mixture of molten salts (Na2CO3 and K2CO3) and nanoparticles (copper), which acts as the absorbing medium and in turn heats the biomass matter (cellulose). A two-stage heat transfer and chemical reaction analysis is carried out in order to simulate the simplified operating conditions of a solar-powered gasifier. The temperature of the molten salt at the exit of the reactor is held fixed at 1000 K (727°C). The calculations are carried out at different values of solar concentration factor ranging from 10 to 60. The results show that the temperature of the molten salt mixture at the exit of the solar collector increases with an increase in the solar concentration factor. Moreover the temperature inside the biomass reactor is a function of the concentration factor as well and largely the determining factor of the rate of biomass conversion into product gases. At the highest concentration factor (Cf = 60), the model predicts that the reactor is able to convert 1.1 tons of biomass into product gases each hour using 900 kW of solar radiation at an overall efficiency of 8%. The main finding of this study is that under similar operating conditions a solar collector using a direct absorption fluid (mixture of nanoparticles and molten salt) would require significantly less concentration factor (an order of magnitude reduction) than a conventional solar collector. A conventional solar collector is defined as one where the solar radiation heats up a solid surface (such as tube walls) which in turn heats up the working fluid (molten salt). Such a reduction in concentration factor would translate into lower concentrator area, and consequently lower initial capital cost.

scholarly journals The Effect of Solar Chimney Dimensions on its Performance in Nasiriya City Weather Conditions

2018 ◽  
Vol 7 (4.19) ◽  
pp. 824
Author(s):  
Rafid M. Hannun ◽  
Hussein Togun ◽  
Mohammed H. Khalaf ◽  
Tariq M. Abed
Keyword(s):  
Solar Radiation ◽  
Solar Collector ◽  
Numerical Study ◽  
Weather Conditions ◽  
Ambient Air ◽  
Previous Literature ◽  
Solar Chimney ◽  
Air Velocity ◽  
Analytical Results ◽  
Air Intake

In this study, a numerical study was carried out on the effect of the solar chimney dimensions on its performance. Five different models of solar chimney were studied in terms of the diameter of the solar collector, the height of the air intake entrance of the collector and the height of the solar chimney. The five models were compared with others according to the conditions surrounding the solar chimney. The study showed that the increase in the dimensions of the solar chimney increases the utilized energy and the external air velocity is inversely proportional to the performance of the solar chimney due to increasing the thermal losses from the collector. The results showed also that increasing the temperature of the ambient air and the solar radiation increases the performance and productivity of the solar chimney. The analytical results of this paper were compared with previous literature studies and showed a great convergence between them.  

scholarly journals Numerical Performance Investigation of Parabolic Dish Solar-Assisted Cogeneration Plant Using Different Heat Transfer Fluids

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Muhammad Sajid Khan ◽  
Muhammad Abid ◽  
Khuram Pervez Amber ◽  
Hafiz Muhammad Ali ◽  
Mi Yan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Solar Collector ◽  
Integrated System ◽  
Operating Conditions ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Pressurized Water ◽  
Parabolic Dish ◽  
Process Heating

Parabolic dish solar collectors gain higher solar to thermal conversion efficiency due to their maximum concentration ratio. The present research focuses by integrating the parabolic dish solar collector to the steam cycle producing power and rate of process heating. Pressurized water, therminol VP1, and supercritical carbon dioxide are the examined working fluids in the parabolic dish solar collector. The aim of the current research is to observe the optimal operating conditions for each heat transfer fluid by varying inlet temperature and flow rate of the working fluid in the parabolic dish solar collector, and combination of these parameters is predicted to lead to the maximum energy and exergy efficiencies of the collector. The operating parameters are varied to investigate the overall system efficiencies, work output, and process heating rate. Findings of the study declare that water is an efficient heat transfer fluid at low temperature levels, whereas therminol VP1 is effective for a higher temperature range. The integrated system efficiencies are higher at maximum flow rates and low inlet temperatures. The efficiency map of solar collector is located at the end of study, and it shows that maximum exergy efficiency gains at inlet temperature of 750 K and it is observed to be 37.75%.

Thermodynamic Performance Evaluation of a Solar Parabolic Dish Assisted Multigeneration System

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Muhammad Abid ◽  
Muhammad Sajid Khan ◽  
Tahir Abdul Hussain Ratlamwala
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Solar Collector ◽  
Integrated System ◽  
Heat Transfer Fluid ◽  
Outlet Temperature ◽  
Parabolic Dish ◽  
Single Effect

The concentration ratio of the parabolic dish solar collector (PDSC) is considered to be one of the highest among the concentrated solar power technologies (CSPs); therefore, such system is capable of generating more heat rate. The present paper focuses on the integration of the PDSC with the combined cycle (gas cycle as the toping cycle and steam cycle as the bottoming cycle) along with the utilization of waste heat from the power cycle to drive the single effect lithium bromide/water absorption cycle. Molten salt is used as a heat transfer fluid in the solar collector. The engineering equation solver (EES) is employed for the mathematical modeling and simulation of the solar integrated system. The various operating parameters (beam radiation, inlet and ambient temperatures of heat transfer fluid, mass flow rate of heat transfer fluid, evaporator temperature, and generator temperature) are varied to analyze their influence on the performance parameters (power output, overall energetic and exergetic efficiencies, outlet temperature of the receiver, and as coefficient of performance (COP) and exergy efficiencies) of the integrated system. The results show that the overall energy and exergy efficiencies are observed to be 39.9% and 42.95% at ambient temperature of 27 °C and solar irradiance of 1000 W/m2. The outlet temperature of the receiver is noticed to decrease from 1008 K to 528 K for an increase in the mass flow rate from 0.01 to 0.05 kg/s. The efficiency rate of the power plant is 38%, whereas COP of single effect absorption system is 0.84, and it will decrease from 0.87 to 0.79. However, the evaporator load is decreased to approximately 9.7% by increasing the generator temperature from 47 °C to 107 °C.

Solar Radiation Model Applied to a Low Temperature Evacuated Tubes Solar Collector

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Oscar A. López-Núñez ◽  
J. Arturo Alfaro-Ayala ◽  
J. J. Ramírez-Minguela ◽  
J. Nicolás Flores-Balderas ◽  
J. M. Belman-Flores
Keyword(s):  
Low Temperature ◽  
Solar Radiation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Solar Collector ◽  
Outlet Temperature ◽  
Radiation Model ◽  
Solar Radiation Model ◽  
Evacuated Tubes

A solar radiation model is applied to a low temperature water-in-glass evacuated tubes solar collector to predict its performance via computational fluid dynamics (CFD) numerical simulations. This approach allows obtaining the transmitted, reflected, and absorbed solar radiation flux and the solar heat flux on the surface of the evacuated tubes according to the geographical location, the date, and the hour of a day. Different environmental and operational conditions were used to obtain the outlet temperature of the solar collector; these results were validated against four experimental tests based on an Official Mexican Standard resulting in relative errors between 0.8% and 2.6%. Once the model is validated, two cases for the solar collector were studied: (i) different mass flow rates under a constant solar radiation and (ii) different solar radiation (due to the hour of the day) under a constant mass flow rate to predict its performance and efficiency. For the first case, it was found that the outlet temperature decreases as the mass flow rate increases reaching a steady value for a mass flow rate of 0.1 kg/s (6 l/min), while for the second case, the results showed a corresponding outlet temperature behavior to the solar radiation intensity reaching to a maximum temperature of 36.5 °C at 14:00 h. The CFD numerical study using a solar radiation model is more realistic than the previous reported works leading to overcome a gap in the knowledge of the low temperature evacuated tube solar collectors.

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