Outlet Temperature Of Solar Collector Research Articles

Improvement of the classical artificial neural network simulation model of the parabolic trough solar collector outlet temperature and thermal efficiency using the conformable activation functions

The outlet temperature and the thermal efficiency predictions of the PTSC are essential parameters in the solar thermal power system. Therefore, it is crucial to have a prediction model that can predict its spatiotemporal behavior to the greatest extent possible. For that, the present study provides improved models of the classical ANN model by using ELU, swish, softplus, logsig, and tansig functions through the exponential transfer function to improve the outlet temperature prediction performance and thermal efficiency of PTSC. The PTSC’s outlet temperature simulation showed that the ANN model of topology 6-2-1 with the conformable swish transfer function (cswish) was the best model among nine other studied models, with an R2 and Radj2 of 0.9988, and MAE of 0.0052. The simulation of PTSC’s thermal efficiency proved that the conformable functions logsig, tansig, ELU and the classical ELU function involved in the ANN model for 6-3-1 achieved better results with approximately 95% precision. With the non-integer activation functions, was reduced a neuron in the hidden layer, which leads to the simplicity of the prediction model compared to the use of the classical activation functions. The proposed activation functions do not require high-performance features according to their execution times. Therefore, it could be a good alternative for engineers to apply in other thermal energy systems to make their prediction models more accessible and practical in the control and optimization process.

Thermodynamic Modeling and Analysis of a Solar and Geothermal-driven Multigeneration System Using TiO2 and SiO2 Nanoparticles

In this study, renewable energy sources including a high-temperature solar parabolic trough collector and geothermal water integrated with a modified Kalina cycle, a combined ORC-EJR cycle, an electrolyzer, an RO desalination unit, and a domestic water heater. SiO2 and TiO2 nanoparticles dissolved in Therminol VP1 are applied as the working fluid of the solar collector. A comparative analysis of introduced working fluids is performed from energy, exergy as well as cost analysis point of view to evaluate their efficiencies. Solar irradiation, ambient temperature, and collector inlet temperature were the parameters investigated to discover their effects on energy and exergy efficiency, solar collector outlet temperature, hydrogen production rate, and freshwater production rate. The highest generated outlet temperature of the solar collector outlet was 693.8 K obtained by Therminol VP1/SiO2 nanofluid. The maximum energy and exergy efficiencies of the proposed system were 36.69 % and 17.76 %, respectively. Moreover, it is found that by increasing the solar collector inlet temperature, the hydrogen production rate decreases while the water production rate increases.

Thermodynamic Analysis, Advanced Non-Linear Dynamic Simulation and Multi-Criteria Optimization of a 100 MW Parabolic Trough Solar Steam Power Plant

Thermodynamic analyses of concentrating solar power plants and optimizing these cycles relying on the energetic and exergetic optimal efficiencies are quite common. However, it is found that just considering the efficiency of the system for performance optimization and neglecting the adverse effects of the plant's wrong operation timings, which is a function of the solar working fluid flow rate, can easily give misleading optimization results. This study's primary goal is to find the optimal operating point of the cycle in terms of the thermodynamic efficiencies considering the system's operating time. Thus, the Sliding Mode Control (SMC) approach is employed to provide a proper mass flow rate for the working fluid from the solar collector field to achieve a precise output temperature from the collectors in different operating conditions. Multi-objective optimization is performed using the Particle Swarm Optimization (PSO) algorithm. The results of power block sensitivity analysis indicate that a 70℃ increase in the solar collector outlet temperature remarkably enhances electricity generation and exergetic efficiency by 67 and 48%. The two-objective optimization shows 22.01%, 2.10%, and 5.46% enhancement in response time, thermal efficiency, and exergetic efficiency, and the three-objective optimization reveals 3.68% and 3.74% improvement in efficiency (thermal and exergetic), respectively.

Identification of the relevant input variables for predicting the parabolic trough solar collector's outlet temperature using an artificial neural network and a multiple linear regression model

The main objective of this study is to present the most influencing input variables for a parabolic trough solar collector (PTSC) outlet temperature through prediction and optimization. Six artificial neural network (ANN) and four multiple linear regression (MLR) models were proposed, validated, and compared in detail. Temperature, wind speed, rim angle, flow rate, and solar radiation were used as input variables. The simulation showed that ANN-1 and MLR with Second-Order Equation (SOE) are the models that yielded the best results with R2 = 0.9984 and R2 = 0.9958 and with an RMSE = 0.7708 and 1.6031, respectively. The sensitivity analysis results of the ANN-1 model trained, with and without biases, showed that the inlet temperature was the most significant parameter influencing the PTSC outlet temperature. Both models yielding the best results were inverted to estimate the optimal input parameter using the trust-region reflective algorithm optimization method. The optimization results showed that ANNi and MLR-SOEi estimated the input temperature with an error < 4.008% and had a very short-elapsed prediction time <0.2277 s. Due to high accuracy and short computing time, ANN-1 and ANNi are more suitable than MLR-SOE for simulating and optimizing the PTSC outlet temperature. Likewise, the MLR-SOE method proved to be a simpler and cheaper alternative than the ANN method.

Experimental and Numerical Evaluation of Thermal Performance of Parabolic Solar Collector Using Water/Al2O3 Nano-fluid: A Case Study

Energy demand keeps growing all over the world and is contributing to climate change. So, fossil fuels must be replaced by renewable energies. Solar energy is the most accessible energy in Iran as well as in many other countries. Parabolic solar collectors appear to be a very promising technology in solar energy absorption. Meanwhile, nano-fluids are known to improve the heat transfer capabilities in comparison with ordinary pure fluids. In this work, an experimental study was applied to solar collectors using water/Al2O3 nano-fluid located in a renewable energy site of Islamic Azad university of Khomenishahr branch followed by numerical simulations. Experimental tests were conducted for 2, 3, and 4 L·min−1 flow rates with pure water and 0.1 %, 0.2 %, and 0.3 % volume fraction of nanoparticles, respectively, with the results validating the numerical simulations. The results revealed that reductions in flow rate and elevations in volume fraction led to increased outlet temperature of solar collector, inlet and outlet temperature difference in collector, tank and radiator, and improved solar collector efficiency. Also, heat transfer coefficient rose with augmenting the flow rate and volume fraction.

Modelling and control of solar-driven humidification\u2013dehumidification desalination plant

This article reports on mathematical modelling and control of a solar-driven humidification–dehumidification desalination plant. Mathematical models for the components are constructed using CARNOT toolbox in MATLAB environment. Model validation has been shown by comparison with published experimental data. Solar collector outlet temperature control is a key parameter to optimize plant performance. In this study, solar field pump flow rate is controlled to maintain the collector outlet temperature at a predetermined set value. Three types of PID controllers are tested. These include PID, nonlinear PID and fractional-order PID. Controllers’ gains are optimized using genetic algorithm technique. The results show that FOPID controller offers a superior dynamic and static performance and can be automatically adjusted to compensate for weather changes.

TRNSYS Simulation of an Evacuated Tube Solar Collector and Parabolic Trough Solar Collector for Hot Climate of Ahmedabad

TRNSYS software provides the possibility to simulate various solar collectors. In this study, A TRNSYS simulations were carried out for Evacuated Tube Solar Collector (ETC) and Parabolic Trough Solar Collector (PTC) for Hot climate of Ahmedabad for yearly basis. Collector surface area is taken as 4.44 m2 and mass flow rate of fluid as 105.394 kg/hr. The maximum temperature of outlet fluid obtained in Evacuated Tube Solar Collector is 200 °C and for Parabolic Trough Solar Collector is 380 °C for same area 4.44 m2 and mass flow rate 105.394 kg/hr. It is also found for Parabolic Trough Solar Collector that during mid-November to January outlet temperature is in the range of 40-50 °C while in Evacuated Tube Solar Collector outlet temperature is in the range of 40-150 °C.

A numerical model for drying of spherical object in an indirect type solar dryer and estimating the drying time at different moisture level and air temperature

ABSTRACTA numerical model for simultaneous heat and mass transfer was developed for solar drying of spherical objects and the object considered is green peas. Solar collector outlet temperature is assumed as drying chamber temperature and justified through energy balance equations. Assumptions are imposed on heat and mass transfer governing equations without losing the physics of the problem. Discretization is performed by finite difference method with implicit scheme. To generalize, the governing equation and boundary conditions are non-dimensionalized. The set of finite difference equations was solved by Tridiagonal Matrix Algorithm and a computer code in MATLAB was developed to solve them. The drying curves showed two stages of drying, initial, and secondary drying stage. At all drying temperatures and drying time, the center moisture was maximum and it was minimum at the boundary. A percentage of 85.67 surface moisture content and 25.33% center moisture was eliminated in the first 1 hr at 348 K. The product should be dried up to 7.45, 4.74, and 3.74 hr at air drying temperatures of 318, 333, and 348 K respectively, to maintain 10% of the product’s initial moisture content. The result is compared with the experimental result from literature and they are found to be in good agreement.

Performance assessment of parabolic dish and parabolic trough solar thermal power plant using nanofluids and molten salts

Summary The present study has been conducted using nanofluids and molten salts for energy and exergy analyses of two types of solar collectors incorporated with the steam power plant. Parabolic dish (PD) and parabolic trough (PT) solar collectors are used to harness solar energy using four different solar absorption fluids. The absorption fluids used are aluminum oxide (Al2O3) and ferric oxide (Fe2O3)-based nanofluids and LiCl-RbCl and NaNO3-KNO3 molten salts. Parametric study is carried out to observe the effects of solar irradiation and ambient temperature on the parameters such as outlet temperature of the solar collector, heat rate produced, net power produced, energy efficiency, and exergy efficiency of the solar thermal power plant. The results obtained show that the outlet temperature of PD solar collector is higher in comparison to PT solar collector under identical operating conditions. The outlet temperature of PD and PT solar collectors is noticed to increase 480.9 to 689.7 K and 468.9 to 624.7 K, respectively, with an increase in solar irradiation from 400 to 1000 W/m2. The overall exergy efficiency of PD-driven and PT-driven solar thermal power plant varies between 20.33 to 23.25% and 19.29 to 23.09%, respectively, with rise in ambient temperature 275 to 320 K. It is observed that the nanofluids have higher energetic and exergetic efficiencies in comparison to molten salts for the both operating parameters. The overall performance of PD solar collector is observed to be higher upon using nanofluids as the solar absorbers. Copyright © 2015 John Wiley & Sons, Ltd.

Performance analysis of a solar-assisted OTEC cycle for power generation and fishery cold storage refrigeration

The cold storage in fishery industry is in great demand in tropical coastal regions. This research proposes an ocean thermal energy conversion (OTEC) based solar-assisted combined power and refrigeration cycle, which can be used for both electricity generation and fishery cold storage application. In this proposed combined cycle, the ammonia/water is selected as the working fluid and the warm/cold seawater is utilized as the heating/cooling source. A two-stage ejector system is introduced, the turbine is used to produce power and the evaporator is used to produce refrigeration output. Besides, a flat-plate solar collector is utilized to increase the heating source temperature. To evaluate the performance of the proposed cycle, a mathematical model is developed and a simulation program is developed; the performance comparison between it and a previous two-stage ejector OTEC cycle is made, which shows this solar-assisted cycle has a slightly lower power-production efficiency of 2.27% but a much higher comprehensive-production efficiency of 7.89% under the given working condition. Furthermore, parametric analysis is performed to guide the theoretical performance of this combined cycle. The results show that the generator pressure, solar collector outlet temperature and rich solution concentration all affect the cycle performance; the entrainment ratio of the first-stage ejector is greatly affected by the rich solution concentration.

태양열을 이용한 이중진공관형 집열기와 냉동기의 열성능에 관한 연구

Abstract: All evacuated tube collector is being constantly studied since it can reduce the conductive heat loss in absorber by using vacuum technology and has advantage of heat transport capacity and quick thermal re-sponse in comparatively small temperature difference. This study investigated the dynamic thermal performance of the solar collector with the control condition of solar irradiance and fluid temperature by using performance experimental apparatus which is combined with solar collector and refrigerator, examined the thermal character-istics in definite temperature range of fluid in constant temperature tank by simultaneously measuring refrigerat-ing performance. As a result of it, I deducted the related equation of collector efficiency and found that mean collector efficiency has increased through quick heat transfer characteristics according to increase of outdoor temperature and irradiance in case of outlet temperature of constant temperature tank 22℃ when set outlet tem-perature of solar collector 25℃ with outlet temperature of constant temperature tank 18℃ & 22℃. Also COP of refrigerator was acquired value of 6.2~7.1 at outlet temperature of constant temperature tank 18℃.

Performance Analysis of a Hybrid Solar Energy Storage System

ABSTRACTIn this work, a method for increasing the storage capability of a solar thermal energy system has been discussed. The system includes two tanks with the flexibility in choosing the best storage medium on the basis of the solar collector's outlet temperature. The results show that using such a hybrid storage system, the storable energy can be increased. Comparing the results with those for simple common storage systems, the extent of improvement was calculated.For verification of the results, a small pilot system was assembled. The test apparatus operated during 2008-2009 cold months and the parameters were recorded. Comparison of the theoretical and experimental results showed a good agreement.

Optimum outlet temperature of solar collector for maximum work output for an Otto air-standard cycle with ideal regeneration

The optimum solar collector outlet temperature for maximizing the work output for an Otto air-standard cycle with ideal regeneration is investigated. A mathematical model for the energy balance on the solar collector along with the useful work output and the thermal efficiency of the Otto air-standard cycle with ideal regeneration is developed. The optimum solar collector outlet temperature for maximum work output is determined. The effect of radiative and convective heat losses from the solar collector, on the optimum outlet temperature is presented. The results reveal that the highest solar collector outlet temperature and, therefore, greatest Otto cycle efficiency and work output can be attained with the lowest values of radiative and convective heat losses. Moreover, high cycle work output (as a fraction of absorbed solar energy) and high efficiency of an Otto heat engine with ideal regeneration, driven by a solar collector system, can be attained with low compression ratio.

Solar desalination using the vacuum freezing ejector absorption (VFEA) process

This paper consists of design analysis and economic evaluation of a solar-assisted vacuum freezing ejector absorption (VFEA) desalination plant with a capacity of 1 mgd and located in Abu Dhabi, UAE adjacent to the coast of the Gulf. The effect on the design and plant cost of variations in several of the operating parameters was investigated. These parameters are: the sea water salinity, the sea water temperature, and solar collector outlet temperature. Two collector outlet temperatures were used, namely 90°C and 120°C typical of flat plate and evacuated tube collectors, respectively. The absorber loop of the VFEA system uses a sodium hydroxide solution with concentration ranging from 0.5 (dilute stream) to 0.6 (concentrated stream). The results indicate that the capital cost of the VFEA system increases by increasing the sea water salinity and sea water temperature. The capital cost of the system decreases when using the higher value of collector outlet temperature (120°C) typical of evacuated tube collectors. The thermal load on the concentrator is also affected by the sea water salinity and collector outlet temperature with the load increasing with increasing the sea water salinity. The load drops substantially for the collector outlet temperature of 120°C as compared to 90°C. Life cycle savings in fuel costs of the solar-assisted VFEA plant were also estimated using a set of economic ground rules with the objective of specifying the optimum collector area which yields the maximum life cycle savings. It was observed that the optimum area increases with increasing the sea water salinity.