Design, Simulation ,construction and Testing of a Thermosyphon Solar Water Heater for a Block in Postgraduate Hostel in Ahmadu Bello University, Zaria
Chapter One
Aim and Objectives of the Work
The aim of the study is to design, construct, test and simulate a solar water heater for the postgraduate hostel in Ahmadu Bello University, Zaria.
The specific objectives of the study are:
- to determine the optimal system size, through a design analysis
- to construct the solar water heater
- to test and simulate the performance of the systems.
- to estimate the cost of the solar water heating
CHAPTER TWO
LITERATURE REVIEW
Preamble
Solar water heaters also called solar domestic hot water systems can be a cost-effective way to generate hot water for domestic use. They can be used in any climate, and the fuel they use, sunshine, is free (Gulland, 2012).
Passive and Active Solar Water Heater
Residential solar thermal installations fall into two groups: passive (sometimes called “compact”) and active (sometimes called “pumped”) systems. Both typically include an auxiliary energy source (electric heating element or connection to a gas or fuel oil central heating system) which is activated when the water in the tank falls below a minimum temperature setting such as 55 °C. Hence, hot water is always available. Solar water heating systems include storage tanks and solar collectors (Walker, 2012).
Passive solar water heater
Systems rely on heat-driven convection or heat pipes to circulate water or heating fluid in the system as shown in figure 2.1. Passive solar water heating systems cost less and have extremely low or no maintenance, but the efficiency of a passive system is significantly lower than that of an active system, and overheating and freezing are major concerns.
Figure. 2.1: Passive solar water heater system (Alternative energy tutorials, 2012)
However, passive systems can be more reliable and may last longer. There are two basic types of passive systems (Walker, 2012).
Integral collector-storage passive solar water heater
It‘s simple; it is an insulated box with a black-painted tank inside and a glass cover that faces the sun. The use of Integrated Collector storage systems in mild climates transcends more than a century of fairly wide popularity (Norton, 2013). In places where freezing temperatures are common Integrated Collector storage units can be used seasonally, and bypassed and drained when winter weather comes. These work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot-water needs.
Thermosyphon solar water heater
Water flows through the system when warm water rises as cooler water sinks. The collector must be installed below the storage tank so that warm water will rise into the tank. These systems are reliable. They are usually more expensive than integral collector-storage passive systems.
Active solar water heater
Systems use one or more pumps to circulate water and/or heating fluid in the system, as shown in figure 2.2
CHAPTER THREE
MATERIAL AND METHOD
Solar Water Heater Description and Operation
The flat plate solar collector of the system was made of mainly an air tight rectangular wooden cased box inclined at an elevation (tilt angle), to maximise absorption of radiant energy as shown in figure 3.1. Its upper part (covering) is made of glass as glazing material. Inside the box is a flat aluminium absorber plate painted black to enhance absorbance of solar energy followed by copper pipe fittings which serve as the fluid tubes.
CHAPTER FOUR
RESULTS AND DISCUSSION
Meteorological and Simulated Solar Data for Zaria and Solar Water Heater Design Parameter
The meteorological data (monthly average daily weather condition of the recommended days of the year) for Zaria, Nigeria (lat. 11.2o N and Long. 7.8o E) is shown on table 4.1. The data was used for the system design calculations.
Table 4.1 Zaria Meteorological data
CHAPTER FIVE
SUMMARY, CONCLUSION AND RECOMMENDATIONS
Summary
The design simulation fabrication and performances test of a thermosyphon solar water heater was carried out successfully for a block in Postgraduate hostel of Ahmadu Bello University Zaria, Which has the ability to heat 200liters of water to a temperature of 45 degree centigrade the design was purposely for students to use the water for bathing in order to totally discourage the use of electric heating devices in the hostel which on several occasions has been the reason of fire outbreaks in the hostel.
The system factors such as costs and sizing were taken into consideration which assisted in the choice of materials and the design drawings. The average solar radiation data was obtained from typical meteorological year (TMY) of Zaria which was used to determine the month with the least solar radiation, from the analysis of the typical meteorological year (TMY) of Zaria the month of August has the least energy ratio which point it out as the month with the least solar radiation and it was used as the design month.
The optimization of the system component was also carried out to determine the optimum system size MATLAB was used for the system optimization.
Finally, the solar water heater conditions were simulated using TRNSYS programme. Typical meteorological year (TMY) solar data of Zaria obtained from www.solaranalytical.com was processed to obtain the monthly average daily solar resources of Zaria using the solar radiation and weather data processor TYPE 109 component of TRNSYS 16 software.
After the fabrication of the system the system performance was evaluated by comparing the simulation result obtained from the model (solar data processor, Type 109 of TRNSYS) and the result obtained from the experiment using Microsoft Excel and also statistical tools where used to validate the predictive power of the model.
Conclusion
- The optimal system size was determined using MATLAB which ascertained the characteristics of component materials with respect to system efficiency and after which the trynsys was used to obtained the system components
- The solar water heater was simulated using trynsys to predicted the system performance before the fabrication, to ensure the efficiency of the system, and also to make all the necessary adjustment so that maximum systems performances will beobtain
- The solar water heater component was fabricated in the mechanical engineering workshop Ahmadu Bello University Zaria, using locally available materials, the components of solar water heater were assembled on the rooftop of Sassakawa postgraduate hostel (BlockK)
- The cost of the system was estimated after the solar water heater was fabricated using locally available
- The solar water heater was tested for three days and the result obtained was compared with the simulated result with was used to ascertained the system performance and
From the result obtained from the research it can be conclude that the thermosyphon solar water heater of collector area of 2.6m2 has the ability to heat 200liter of water to an temperature of 50oC in the month that has the least solar radiation in Ahmadu Bello University.
The statistical tools used for the validation of the simulation model confirm that the model is valid and can be used in the estimation of the actual characteristics of a real system, which a good accuracy the relative error is very minimal for all the measured parameters and Nash-Sutcliff coefficient shows that the degree of fitting is very high which shows that the simulation model has a high accuracy and also the standard deviation shows that the deviation of the experimental parameters from the simulated is very low and therefore it is negligible.The results show little deviation of predicted values from actual values and also a good level of fit, thereby validating the model used for simulating the solar water system
Recommendations
- Auto tracking reflectors incorporated into the design will also enhance the efficiency as the effect of shading is minimized due to the shift of the reflector with the movement of the sun; it will redirect sunrays falling at the side of the collector unto the absorber plate.
- It is also recommended that the hot water should be separated from the cold water and devices that can control the flow of cold water and the cold water should be incorporated so as to increase the efficiency of the
- The adjusting mechanism for setting the collector to the specified latitude of the area is to be designed to further improve the systems
REFERENCES
- Ahmad, A. R.(2010) Theoretical Analysis Of Solar Water Heating System. Faculty of Mechanical Engineering University Malaysia Pahang.
- Alternative Energy Tutorials. (2012). Alternative and Renewable energy. Retrieved July 20,2012 from http://www.alternative-energy-tutorials.com/.
- Brandemuehl, M. J. and Beckman, W. A. (1980), ―Transmission of Diffuse Radiation through CPC and Flat-Plate Collector Glazings,‖ Solar Energy, 24: 511-524,
- Crawford, R. H., Treloar G.J. Ilozo B.D. and Love P.E.D (2003), Comparative greenhouse emissions analysis of domestic solar hot water systems. Journal Building Research & Information, Volume 31, 34–47.
- Christopher A. Homola, P.E . (2010)Solar domestic hot water heating system design, installation and maintenance. Retrieved Jan 20th 2012 at
- http://www.solar- rating.org
- Duffie, J.A. and Beckman, W.A (1991). Solar engineering of thermal processes, 2nd Edition, Toronto :John Wiley & Sons.
- Dobson, T. (2008) Solar Water Heating Theory. [email protected]
- Gulland, J.(2012) “Heating water with a wood stove”. woodheat.org. Wood HeatOrganizationInc.. Retrieved 29 March 2012.
- Govind, N.K., Shireesh, B.K., and Santanu, B. (2008). Design of solar thermal systems utilizing pressurized hot water. Solar Energy, 82 (23), 686–699.
- Henry, H. D. (2010) Design and construction of a solar water heater for the microbiological laboratory sick bay. Unpublished B.Eng Degree Project Report.Department of Mechanical Engineering.Ahmadu Bello University, Zaria. Nigeria.
- Holland , K.G.T (2005) Free convection in solar collectors.Progress in Energy and Combustion Science 30:231–295 Retrieved January 27, 2013 from http//:www.elsevier.com/locate/pecs.
- Hottel H.C and Woertz, B.B (2004) Performance of flat plate ASME pg 91-104 Feb. 2004
- .Taherian .H ,RezaniaH.Sadeghi .A, Ganji D.D (2011) Experimental validation of dynamic simulation of the flat plate collector in a closed thermosyphon solar water Energy Conversion and Management 52: 301–307 Retrieved February 27, 2013 from http//:www.elsevier.com/locate/enconman
- Institute Sustainable Technologies (2001) ―Solar Thermal Systems and Components‖ ISO 9459-3:1997(E). (1997). Performance tests for solar plus supplementary systems.
- international standards organization, Geneva, Switzerland