Variational method in the design of an optimum solar water heater storage tank

Solar energy is a renewable resource because it is non-exhaustible and is available in abundance. The average daily total solar radiation amount in Malaysia is about 4500 Wh/m2, K.S Ong (1994). Intermittency and non-availability at night are the main drawbacks to the use of solar energy. However, heat storage devices could be designed to store heat for up to 24 hours if necessary. Solar water heaters are now been accepted as a reliable source of providing hot water heating in many domestic homes and are becoming more popular. Unfortunately, solar water heaters are still considered luxurious items in Malaysia. Users will always seek the product with cheaper price but at the same time still fulfill their need. Thus, a cheaper and efficient solar water heater system is required to be designed. The only way to produce cheaper and efficient product is through the optimization process to obtain the minimum cost but still maintain the specification required or call as constraints. In this project the hot water storage tank will be analyzed to obtain the optimum cost. Thermosyphon-flow solar water heating system is preferred for obvious economic reasons since they do not require circulation pumps and control units. Average temperature of the hot water in the storage tank is determined through the temperature distribution simulation. The overall average temperature obtained is 49.30C. The overall average temperature is used to solve the optimization problem. The constraints involve for the optimization are the tank volume and heat losses allowed from the water in the tank. The Lagrange multiplier method, which is based on derivatives of the objective function and the constraints are applied. The optimum independent variables and Lagrange multipliers is solved by computational approach. The minimum cost obtained for hot water storage tank with 225 l capacity is RM 1322.15. The Lagrange multipliers represent the sensitivity coefficient, which define as the rate of change of the objective function with the constraint at the optimum. This optimization method is very useful for the manufacturer in adjusting the design variables to come up with the final design

Variational method in the design of an optimum solar water heater storage tank

Solar water heaters are now have been accepted as a reliable source of providing hot water heating in many domestic homes and are becoming more popular. Unfortunately, solar water heaters are still considered luxurious hardware in Malaysia. A cheaper and efficient solar water heater system is required to be designed. The only way to produce cheaper and efficient product is through the optimization process to obtain the minimum cost but still maintain the specification required or known as constraints. In this paper, the vertical water storage tank will be analyzed to obtain the optimum cost. Thermosyphon-flow solar water heating system is preferred for obvious economic reasons since they do not require circulation pumps and control units. Average temperature of the hot water in the storage tank is determined through temperature distribution simulation. The overall average temperature obtained is 49.3ºC and is used to solve the optimization problem. The constraints in the optimization process are the tank volume and heat losses from the water in the tank. The Lagrange multiplier method, which is based on the differentiation of the objective function and the constraints is applied. The minimum cost obtained for storage tank volume of 225 litres is RM 1321.6

Comparison Between 2D and 3D Simulations of a Tray Dryer System Using CFD Software

The tray dryer is the most extensively used drying system because of its simple and economic design. The drawback of this dryer is the non-uniformity in the final moisture content of the product. This research aims to predict the temperature and velocity profile in the drying chamber using computational fluid dynamics simulations. Two 3D designs of drying chambers (cases 1 and 2) were studied. Both designs have the same dimensions, except for the geometry of the inlet and outlet boundary conditions. The simulation was performed in 3D, but the analysis was carried out in a 2D plane. Another 2D simulation (case 3) was carried out to compare the results with those of the 3D simulation. The design in case 2 can be represented in a 2D simulation, whereas the design in case 1 must be represented in a 3D simulation. The 3D simulation can be simplified into a 2D simulation if the geometry and boundary conditions in the 3D simulation are the same as those in the 2D simulation at any position of the plane parallel to the 2D drawing. The 2D simulation is simple and saves time in terms of design, meshing and iteration processes for achieving convergent solutions

Review on the Application of a Tray Dryer System for Agricultural Products

Application of tray dryer is widely used in agricultural drying because of its simple design and capability to dry products at high volume. However, the greatest drawback of the tray dryer is uneven drying because of poor airflow distribution in the drying chamber. Implementing the proper design of a tray dryer system may eliminate or reduce non-uniformity of drying and increases dryer efficiency. This paper discussed several design of tray dryer system for drying agricultural products and its performance. Most of the dryer systems have been developed are using solar energy because the systems run at low operating cost. Computational fluid dynamics simulation is a very useful tool in the optimization of the drying chamber configuration by predicting the airflow distribution and the temperature profile throughout the drying chamber

Comparison of CFD Simulation on Tray Dryer System Between Porous and Solid Product

Tray dryer is the most widely used because of its simple and economic design. The product is spread out on trays at an acceptable thickness. In a tray dryer, more products can be loaded as the trays are arranged at different levels. Most tray dryers use hot air stream where water is vaporized from the product and removed by air stream. The drawback of this dryer is non-uniformity in the desired moisture content of end product. The key to the successful operation of the tray dryer is uniform airflow distribution over the trays. Therefore, the good design of the drying chamber configuration in a tray dryer is necessary to obtain optimum performance. This research is to design the uniform airflow distribution throughout the drying chamber using CFD simulation. The products are represented by porous and solid (non-porous) product. Several configurations of trays position also was designed and simulated to determine the tray dryer with better airflow distribution. It was found that by using porous product the overall velocities in the drying chamber are lower than solid product since some of the hot air stream pass through the porous product. The design C was recommended to be developed for both porous and solid product which can produce more uniform drying and shorter drying time because of good temperature and velocity distribution throughout the drying chamber

TDS and pH Analysis for Water Quality Monitoring in Water Hydraulics Food Processor

This study proposes a low-cost water hydraulics food processor for a traditional cookies production. The hygienic, safe and low maintenance cost characteristics of water should provide interesting viewpoints due to concern over issues in hydraulic fluid contamination, flammability, disposal, and costly maintenance. The objective of this project is to introduce the design and the working principle of the water hydraulics-driven food processor, and to determine production process performances and capabilities. In this paper, results of the corrosion monitoring of the test bed is presented. PLC is used in the testing of the machine, by creating an automatic movement of the cylinders. The Total Dissolved Solids (TDS) and pH analysis of the water hydraulics quality used in the process is discussed

Technology Progress On Photovoltaic Thermal (PVT) Systems With Flat-Plate Water Collector Designs: A Review

Commercial solar cells are currently less efficient in converting solar radiation into electricity. Photovoltaic (PV) performance decreases as temperature increases. Many efforts have been made to investigate and develop hybrid PV and thermal collector systems. A photovoltaic thermal (PVT) system generates both electric power and heat simultaneously. A significant amount of work has been carried out on these systems since 1970. Different PVT systems have been invented in the last 30 years. The aim of PVT systems is to improve electrical efficiency using a cooling system by reducing cell temperature, and an absorber collector takes the excess heat underneath the PV system. Then, the heat is transferred through working fluids such as water. The harvested heat is further used in low-temperature applications, including domestic hot water supply, water preheating, and space heating. This work shows the developments of the PVT systems, development of PVT systems with spectrum filters in recent research, the development and design of flat-plate water collectors in PVT systems, including various types of flat-plate solar collectors, and also a broad classification and review of published research work on the systems. The performance of PVT-based water collectors is determined by different combinations of absorption collectors and solar collectors as important elements of PVT systems. New design ideas and innovative configurations have emerged, especially when liquid as a medium of heat transfer is utilized to obtain useful heat from the back surfaces of PV panels. Various design configurations for hybrid PVT collectors are also compiled and assessed, and the emphasis is on the design performance of absorbers. The findings show that solar collector design parameters can easily affect and enhance the overall performance of PVT systems, especially electrical and thermal efficiency. The general performance of PVT systems may have benefited significantly from the extensive research conducted on this topic since the last decade. In order to develop novel PVT systems, more effort is needed in accurate modelling, exploration of novel materials, enhancement of PVT system stability, and the design of a supporting energy storage system

Numerical Investigation And Performance Analysis Of Photovoltaic Thermal PV/T Absorber Designs: A Comparative Study

The term of PV/T refers to the solar energy system which is associate the photovoltaic and solar collector with each other in order to improve the photovoltaic efficiency. This system generates both thermal and electrical energy simultaneously. The aim of this work is to investigate numerically and comparing the performance of PV/T system with two absorber designs. A new photovoltaic thermal (PV/T) collector called serpen-direct is designed and compared with serpentine PV/T design. Theoretically, the PV/T performance for serpen-direct flow is validated and compared with the conventional serpentine flow design using MATLAB Simulink. Parameters, such as outlet water temperature, cell temperature and PV and thermal efficiency, were tested under various mass flow rates that range from 0.01 kg/s to 0.1 kg/s and two-level solar irradiance 300 W/m2 and 700 W/m2. Results show that the serpen-direct flow absorber design provides a better system performance than the serpentine flow design under the same operating conditions. The maximum PV and thermal efficiencies are 12.51% and 57.66%, respectively, for the serpen-direct flow and 12.43% and 54.68%, correspondingly, for the serpentine flow design

Performance Test of Solar Assisted Solid Desiccant Dryer

The solar assisted solid desiccant dryer was designed and developed to dry agricultural product. The experiment was carried out to study the performance of the component in the dryer system and drying air condition without load. The system can produce drying air at average temperature 52oC under average solar radiation of 797 W/m2 which is suitable for heat sensitive product to maintain the fresh color, taste and nutrient content. The collector efficiency, heat exchanger effectiveness 1 and 2 was 70%, 77% and 67%, respectively. The thermal, regeneration and dehumidification effectiveness was 48%, 29% and 6%, respectively. The poor performance of desiccant wheel may be improved by increasing the regeneration temperature above 65oC. Some improvements are still required to improve the overall performance of the system such as decrease the regeneration air flow rate, increase electrical heater power and using direct connection from the solar collector to the dryer system

Simulation of air flow distribution in a tray dryer by CFD

Application of tray dryer is widely used in agricultural drying because of its simple design and capability to dry products at high volume. However, the greatest drawback of the tray dryer is uneven drying because of poor airflow distribution in the drying chamber. Implementing the proper design of a tray dryer system may eliminate or reduce non-uniformity of drying and increases dryer efficiency. This This study investigates the airflow distribution throughout the drying chamber by using Computational Fluid Dynamics simulation for kenaf core drying. The experimental and simulation data exhibit very good agreement. The drying rate of dried products in each tray was predicted using the validated data. The result shows that, the higher the air velocity, the higher the drying rate of the products. The alternate arrangement of tray position was adopted to ensure that all trays are exposed directly to drying air and to improve airflow distribution throughout the drying chamber. There was a variation of final moisture content for product at different columns. As the distance of product far from the air inlet, the air velocity decreased. However the uniformity of air flow distribution to each level of product at the same column are acceptable