Introduction
Solar heaters have been popularized in recent years for use in tertiary and residential areas. This has happened mostly in the third world countries. The reason behind this encouragement to use solar heaters is the reduction of cost and improving the performance. This has necessitated the use, and testing of solar heaters to produce hot water. The solar heater is fundamentally made up of tanks that act as solar absorbers ad storage bases for warm water. This is used in glazing to profit the green house effect and the insulating cases. The solar heaters can be made from ordinary manufacture, maintenance, and use. The energy performances have indicated effectiveness in producing hot water. The solar panels can increase the temperature of water to about 70°C when there is enough sunlight. This gives efficiency of around 7% (Helal, Chaouachi, Gabsi & Bouden, 2010). This is the reason the solar panels are available to be used in larger mass. The paper is going to focus on how a solar heater works to produce hot water.
Solar heaters
Most countries have a latitude profit in the sunning winter. The average solar flow for such countries is between 8 kWh/m²/d during summer and 3.5 kWh/m²/d in the cold winter season. This flow is at around 6 kWh/m²/j when the sun is above the equator (Faiman, Hazan & Laufer, 2001). Subsequently, the heating of water becomes possible through the use of solar energy. This is possible without reaching a 100% of hot water in winter. A standard solar heating system has an integrated storage mechanism. This mechanism should have a strong value of insulation fraction, which makes the systematic recourse of the thermo siphon solar water heater not to be justified (Helal, Chaouachi, Gabsi & Bouden, 2010, p. 158). The design tests the realization of the solar water heater that has an integrated storage collector meets the required standards. The heaters are inexpensive, easy to use, and reliable as they use locally available materials for construction. The standard water heater called Compound Parabolic Concentrator (CPC) and many other water heaters collect the solar radiation. The solar radiation is diffused towards the sun. The temperature of the water can pass the 70°C in a day with adequate sunlight (Faiman, Hazan & Laufer, 2001). During the night, the cooling does not affect the solar heaters. This is because the sunning days are many and the fraction of the insulation is high.
There are numerous varieties of solar water heaters. In the Scandinavian countries, the solar water heaters have the collector that is placed outside on an inclined roof (Figure 1). This is coupled by the inside storage balloon that is used to reduce the cooling by use of the external ambient air. The range needs a regulation and pumps for operation purposes. There are the thermo-siphon solar water heaters, which have the balloon located at the roof. This makes it possible for a diurnal natural circulation of the heated water in the collector as it flows to the storage balloon. The integrated storage collector in a solar water heater is another type of these heaters. The heaters come in various forms namely; multitubular or monotubular, and planes (Romdhane, 2102, p. 68). The integrated storage collectors are improved and basic parallel plane collectors of solar heaters. The solar concentrator is of the design of the CPC and has separated compartments of storage and collector. In addition, the solar heater has a tank from the collector that has integrated storage. They use a refrigerant in conveying the heat from the collector compartment to the storage compartment.
The plane collector has storage integrated with a slab that insulates the interior to separate the water volume into two sections. These are the section for water collection and storage. The integrated storage collector has a thermal diode that helps in avoiding the night circulation of the water out of the thermo siphon reserves. Therefore, this reduces the cooling that is often associated with the solar water heaters. The integral compact solar water heaters are integrated, with a channel, and water tank, to help in minimizing the thermal losses. The transparent insulation materials are also used in improving the solar water collector for the climate. The polycarbonate honeycomb material is used, and this improves the performance as the temperature range from 80°C to 140°C (Faiman, Hazan & Laufer, 2001). The natural convention in the air cavity that is located between the cover plate and absorber forms a water cavity in the water storage tank. The increase in the angle of inclination in any latitude can advance the thermal presentation of the solar water heater. The ICS vessel that has an inner sleeve should be used to reduce the heat loss at night. The ICS has transparent insulation that helps in reducing the heat loss and giving accuracy of the thermal performances.
The solar heaters can have cylindrical tanks that minimize the thermal losses from the absorber to the ambient. This can be compared to the conventional solar water heater. The heat retention can be done by the utilization of the vessel in ICS. This CPC has a pressure water resistance and a reduced night cooling. In addition, these ICS are complex to realize when compared to the plane collectors. The direct solar radiation is the only energy used in concentration when the continuation of the sun is needed. This becomes a problem when the heating is of low temperature.
How the Solar Water Heater works
The solar water heaters are based on a design that looks like a tank. The heater is painted in black so as to soak up warmth from the sun. This heat is transferred to the water that is stored within the tank. The heaters have a batch where the water is stored. The storage tank is enclosed in an insulated box that is covered at the south facing the side. The top, as illustrated in figure 2, is made of a glazing material that can be molded plastic or glass. This combination helps in reducing heat loss and increasing heat collection. The solar water heater has a benefit to the environment. This is because the heater uses the sun’s warmth to reheat the water. This is instead of using an electric element or gas burner. The sun has replaced the hydrocarbon fuel that is mostly used in heating. This has a significant impact on the environment. There is the reduction of pollution, carbon emissions, and the cost of transport and extracting energy fuels are reduced. The solar water heater needs a convenient location. This is because the system relies on the thermosyphon in the circulation of the water. The thermosyphon works by using the water in the collector that warms up (Faiman, Hazan & Laufer, 2001, p. 89). The water becomes less dense and move upwards, and this pulls the cold water into the collector. The collector needs to be in a lower position than the water tank so as to function effectively. In addition, this helps the hot water to rise into the tank.
The energy use is cut by use of high efficient solar water heaters. The planetary water heaters are used mostly with the conventional heaters. This is because the weather affects the solar hot water production. Thus, the conventional heaters can be used in supplementing the solar heaters. The solar water heaters reduce the energy bills and the CO2 emissions. The solar is a clean energy source. The fuel and sunlight from the solar are free, limitless, and emits nothing when they are converted into energy. However, the efficiency of the solar is the problem. The photovoltaic technology or PV of the solar is less efficient when converted from fuel into electricity. Although, this is the case, using the solar energy to warm water as opposed to powering stereos or light bulbs, the sunlight does not need to be electricity. The energy needed is heat and turning the sunlight to heat is not a massive problem.
The solar water heater uses sunlight in warming water. The heaters have solar collectors that consist of copper pipe coils inside them. These coils are used to heat up and transfer non toxic and food grade propylene glycol, which flows slowly as the temperature of the liquids is increased in the collectors. It is necessary to note that the temperature depends with the type of collector and material used. As the propylene glycol heats up, it streams down to heat the water; this is achieved by the utilization of a heat exchanger. Subsequently, the propylene glycol flows back into the collectors to reheat (Smyth, Eames & Norton, 2006, p. 512). It is essential to note that this fluid does not come into contact with the warm hose for the house as the heated water is kept in the large storage tank. This is necessary to allow for the morning shower water to be heated by the sun from the proceeding day in a process which involves a high tech version of the sun energy systems. The solar systems provide about 80% of hot water for domestic use (Smyth, Eames & Norton, 2006).
Conclusion
The solar water heating systems have excellent economic payoffs. They are manageable systems that are easy to build and install. In addition, the designs of the solar water heating are straight forward and have low cost. The heaters have clear batches that can be used in warm climates. They can be used in closed loops and drain back systems. The energy used by the solar systems is from the sun. This energy is inexhaustible and free. The solar water heaters work by the installation of the thermal panels on the un-shaded south facing portion of the roof. The panels collect heat from the sun’s rays. The heat warms the liquid that moves through the pipes that are connected to the panels. The liquid is the heat transfer fluid such as anti-freeze or water from the home. The use of heat-transfer fluid calls for the use of a heat exchanger where the fluid flows in the water heater. This warms the water like the gas or electric heater.
References
Faiman D., Hazan H., and Laufer I. (2001). Reducing the Heat Loss at Night from Solar Water
Heaters of the Integrated Collector. Solar Energy, 71(2), 87-93.
Helal O., Chaouachi B., Gabsi S., and Bouden C. (2010). Energetic Performances Study of an
Integrated Collector Storage Solar Water Heater. Journal of Engineering and
Applied Sciences 3(1), 152-158.
Romdhane, B. (2012). Experimentation of a Plane Solar Integrated Collector Storage
Water Heater. Energy and Power Engineering, 4, 67-76.
Smyth M., Eames P. C. and Norton B. (2006). Integrated Collector Storage Solar Water Heaters.
Renewable and Sustainable Energy Reviews, 10(6), 503-538.
