Solar Water Heater - Coursework Example

Overview Hot water represents the second largest energy consumer in households, yet solar water heaters reduce the carbon emissions and electrical consumption. We have provided the best solution of solar water heaters. This solution is called the drain back solar water heater system. We use Solar Plates to heat the coolant and transmit the heat to the drain back tank, which then heats the water and stores it in an insulated tank. This Solar Water Heating System provides the homeowners to ability to realize the economic and environmental benefits of heating their water in Ontario. Analysis of problem and solution There is one best solution to reduce the carbon emissions in the water heater industry. In total, there are three kinds of water heaters on the market: gas water heaters; electricity water heaters; solar water heaters. The solar water heater is the best solution to reduce the carbon emissions in the water heater industry. Solar water heaters are very environmentally friendly technology that is very cost efficient. The solution is to input solar water heaters in every household in Ontario. To use the solar water heaters in Ontario, Canada, we need to meet several key point requirements. We also need think about our climate, and select the best solution. The solar water heater can work in winter at a lower temperature, and have the anti-freeze function. This system can support the homely usage, with the average being between 3 to 5 people per home. The solar water heater must have no carbon emissions and a lesser electricity consumption. Did the solar water heater meet these requirements? If you want to fully realize this problem, we need to discuss the various types of solar heater systems first. The principle of the solar water heater system is based on a series of painted flat plates used to absorb heat from the sun to heat the water. The solar water heater can provide a big saving on electricity consumption due to this. The solar heater system that we are discussing is not for charging photoelectric cells and then heating the water; it is for heating the water directly or indirectly. There are two basic types of the solar water heaters: active and passive. These two kinds can provide the homely usage depending on the size of the tank. The main difference between these types is the use of external power: While active solar heater systems use fans or heat pumps to circulate and transfer the heat energy, passive solar heater systems heat the water by using the solar energy directly. The passive solar heater system is not very effective while being used in winter at lower temperatures, and it has poor anti-freeze function. So we must select the active solar heater solution and it is called the Drain back solar water heater. Technical descriptions of mechanisms, tools, facilities, or products used in solving the problem Drain back solar water heater The drain back solution is a downside to the closed loop antifreeze system design. This solution has satisfied with homely daily responsibilities and has the best heat efficiency performance. Without circulation to remove heat from the collectors, temperatures can climb to as high as 400°F (204°C). Although this solution is named drain down type system, the drain back system is far different and much more reliable. It has more advantages than the passive solar water heater. The drain back system uses coolant as the heat transfers liquid inside the solar collectors. This kind of liquid can provide best performance of freeze protection from poor drainage and controller or sensor malfunctions. The circulating pump is turned on when the temperature of drain back outlet is 20°F (11°C) warmer than the storage tank outlet. The colder water is lifted from a small reservoir tank and circulated through the drain back tank and back to the hot water tank. Heat is transferred to the domestic water via a heat exchanger in the drain back tank. The circulation loop through the drain back tank is a closed loop. A drain back system requires more pumps than the passive solar solution. It must have sufficient capacity to lift the fluid to the highest point in the system. When there is no more heat to be collected, the controller turns the pump off, and the coolant has the lower freezing point and cannot be frozen in winter. Solar Plate A flat plate solar thermal collector usually consists of copper tubes fitted to a flat absorber plate. The most common configuration is a series of parallel tubes connected at each end by two pipes, the inlet and outlet manifolds. The most efficient collector design maximizes solar heat gain, minimizes heat losses, and provides for the most efficient heat transfer from absorber plate to tube. For the highest efficiency solar thermal collector, we used the evacuated tube collector, such as the one manufactured by Thermomax. Although evacuated tube collectors are more efficient than conventional flat plate collectors, they cost approximately twice as much per square foot. The tube and fin of the collector are contained within a glass tube from which all the air has been evacuated. Since air carries heat from the hot surface of the tube to the cooler surface of the glass, there is an acceleration of heat loss by convection. Eliminate the air and you have eliminated convective heat loss. To minimize the loss of radiant heat, the tube needs to be covered with a selective surface. Evacuated tube collectors are meant mainly for high temperature applications (over 140°F; 60°C). They are useful for more commonly low temperature applications too, such as water and space heating. This solar heater system is designed especially for colder climates. The simple part of the heater contains a series of solar collection tubes and a coolant in the unit solar tube plate. The vertical pipes are vacuum tubes with heat pipes. The pipes inside the glass tube vacuum is made of copper tubing. The coolant is evaporated when the sun heats the tube. Then the coolant vapours are transmitted to the drain back tank, therefore heating the cold water. Tanks -- Separate Storage The design of the drain back system has the effectiveness of collector and storage functions. Heating water continually at the drain back tank will keep the useful temperatures. Inside the drain back tank, increase the surface area of water pipe, compared to the amount of water being heated, and its temperature will rise more quickly. The storage tank can keep the hottest water, and pump the colder water to the drain back tank and return the hottest water back. Cold water, which normally goes to the bottom of your water tank, is detoured to the drain back heater tank first. This cold water should be heated by the coolant which has been baked in the sun. Water only flows when used or the temperature of the bottom of the storage is much lower than the temperature defined. House water pressure also causes the supply of new cold water to flow to the inlet of the water heater, the lower of the two ports. Simultaneously, the hottest water exits from the higher port and flows to the water faucet and to be used by the consumer. This solar heat water system design separates the drain back tank and the storage tank. This can optimize both functions, so that one tank is just for heat, and the other is for storage and insulates the hot water. This design also has the advantage in freezing climates. By separating the drain back tank and the collector, you can put the drain back tank and pipe indoors and away from the freezing environment, and insulate them better for greater efficiency, and only the collector and coolant, freezing protector parts can remain outside. Reference http://en.wikipedia.org/wiki/Solar_water_heater http://www.azsolarcenter.com/technology/solarh20.html http://www.espressomilkcooler.com/solar_hot_water_system_with_self_contained_perpetual_power_supply.htm http://environment.about.com/od/renewableenergy/a/solar_water_hea.htm Read More