Solar water heaters: an analysis and discussion of thermosiphons - Essay Example

Section/# Solar Water Heaters: An Analysis and Discussion of Thermosiphons In the United s alone, approximately 3000 kWh per year are utilized for each individual as a means of heating water. As such, this represents the second highest energy need after heating and cooling. Due to the fact that hot water has become a fixture of the developed world and is required in all societies, seeking to utilize more efficient means of hot water generation is something that engages environmentalists and engineers alike. The current methods of hot water generation within the United States rely on electricity or gas from the grid to heat units within individual hot water heaters. Although the efficiency of these units have greatly increased over the years, they are still inefficient as compared to some of the alternatives that exist. For many hundreds of years, solar energy has been utilized the heat water. This has traditionally been done by means of storing water in a blackened vessel that soaks the Sun’s rays and consequently heats the water contained therein. However, with the revolution of solar energy well under way, there are two means whereby solar water heaters can be utilized to speak to the individual hot water needs that society demands. These are traditional solar cells dedicated to the process of hot water generation and thermosiphon solar water heaters. As a function of understanding how both of these operate, the proceeding analysis will contain a description of each as well as a discussion of some of the distinct advantages and disadvantages that both of these approaches necessarily portend. Firstly, the traditional solar cells that utilize solar energy to power a warming unit within the traditional electric hot water heater are efficient as well as increasingly affordable due to the ever increasing availability of solar systems; however, due to the fact that they require a large surface area in order to capture the Sun’s rays, they are oftentimes not utilized due to the fact that other demands from solar systems are often utilized. The distinct advantage of this traditional form of solar energy is that it can be diverted to other systems when and if the hot water is not longer required. However, the main disadvantage is the total level of surface area that must be covered by solar cells in order to generate the requisite power that is necessary to heat a traditional drum of otherwise cool water to the temperature that is utilized for domestic purposes. Figure 1.0 aptly demonstrates the means by which such a traditional solar powered hot water heating system functions. As can be seen in the diagram, the solar cells power the traditional hot water heating unit that in turn utilizes the Sun’s rays to warm the water. As such, it can be noted that the process for heating traditional hot water heaters utilizing traditional solar power via solar panels is rather self explanatory albeit somewhat inefficient. Although this approach is efficient, it pales in comparison to the thermosiphon with respect to the overall amount of energy required to heat 1 gallon of water to appropriate temperatures. Figure 1.0 Likewise, the main portion of this particular research will focus upon the ways in which thermosiphon hot water heaters can and should be utilized to heat water. Firstly, it is worth discussing the means whereby the thermosiphon hot water heater operates. Ultimately, the thermosiphon water heater uses the sunlight to strike tubes and fins within a mechanism that looks very similar to a solar panel. As the heat buildup occurs within this unit, it causes a type of fluid movement as the result of heat differentials throughout the system. In this way, the heat is moved from the collection panels into the collection tank and circulates and distributes among an array of fine tubes within. This is a natural convection process and allows for a nearly constant exchange of energy within the system as long as the heat buildup is occurring between the collection diaphragm and the internal storage compartments. Figure 2.0 illustrates the means whereby the convection process of heat energy is utilized within the thermosiphon in order to process the super heated water as a means of warming the tank as a whole. Figure 2.0 As with any type of thermo generator, it is necessary to position the thermosiphon within the area that will accrue the strongest and most direct level of sunlight at any given time of year. Such a level of forethought is best to consider as a function of the fact that seeking to move such a device in order to utilize a bit more solar energy is not only risky and difficulty but a process that jeopardizes breaking many of the smaller components within the thermosiphon.1 Accordingly, it is generally advisable to seek to place the thermosiphon either on the roof of a building or residence, as a means of ensuring that a very small percentage of shadows and obstructions will impede its ability to soak up the Sun’s energy, or to place it on the ground level in a place that is guaranteed the maximum level of solar exposure year-round. Figure 3.0 illustrates the way that a thermosiphon appears mounted on ground level. Figure 3.0 A further issue of primary importance is ensuring that the bottom of the tank is above the collector. This may seem counter intuitive at first; however, it is important to realize that without placing the bottom of the tank above the collector array, a reverse flow of hot to cold will take place during the evening hours when the Sun’s rays are obviously not able to heat the tank. As the process of convection is reversed, warmer water will be dissipating into the array and cooled by the air during the evening hours. Naturally, such an eventuality will result in an individual having an exceptionally cold shower in the morning hours unless he/she follows the aforementioned instructions regarding ensuring that the tank is mounted above the collection panels illustrated above in Figure 3.0. With regards to installation and the instructions that would necessarily be included for a thermosiphon system, the reader can and should pay a special attention to the amount of research and pre-preparation that goes not only into selecting the location that will maximize output but ensuring that the area is prepared adequately for the system to be installed. Almost all failures that have been experienced and reported from the thermosiphon systems have necessarily been the result of overzealous installation, movement after installation, or failure due to an unprepared or non-reinforced surface or structure upon which the system itself will be mounted. Accordingly, the third portion of this analysis will focus upon the means whereby the user can and should follow a very strict protocol with regards to installing the system. As such, one of the first considerations that should be determined is whether the unit is to be mounted on a roof, structure, or placed upon the ground. Such a determination is important due not only to the earlier question which has been raised with regards to which of these arrangements provides the most solar energy but also due to the fact that if the unit is to be mounted on a roof or structure of any form, it is necessary to undergo a very intensive process of analysis onto the means by which the structure or roof is capable of supporting the weight that will be required of it. This oversight often occurs due to the fact that the installer does not consider the weight of the water plus the weight of the unit itself before installing. However, due to the fact that one gallon of water weights approximately 8.33 pounds, it is necessary for the installer to factor this in when deciding to mount the unit on a structure or on a roof; thereby requiring a rather extensive level of reinforcement. Due to the fact that roofs especially are not intended to support such a level of additional weight, oftentimes the process of installation will require that the individual expends the lion’s share of their time. Similarly, it is important for the installer to be mindful of any falling objects or lose components before during and after the installation process. With regards to the installation of the equipment itself, most aspects of the process are rather self explanatory or easily understood. However, with regards to the assembly of the vacuum tubes that form the backbone of the system, it is vitally important that the directions and cautions that are listed must be followed explicitly. This is due to the fact that unlike the stand upon which the system itself rests, any damage or incomplete/partial or erroneous assembly of the vacuum tubes will cause the entire system to not work or to malfunction within the future. As a function of this, it is oftentimes highly encouraged to seek professional assistance with regards to the installation process. A level of caution must be engaged with regards to hoisting the final product onto the structure or roof that is to be utilized due to the fact that the internal tubing can snap and rupture if special care and consideration is not taken. There is an additional level of maintenance and sustainment that must be performed for the device to function properly. This usually consists of making sure that the convection panels are free from obstruction and/or any type of residue buildup. However, an additional level of care must also be taken with regards to the existence of damage within the system as a function of hail. Though the convection tubes are rated to withstand hail of a limited variety, there are many instances in which severe weather patterns can produce hail larger than can be absorbed by the thermosiphon. Additionally, whether glycerin or water is utilized within the convection panels, it is important to check these levels on a semiannual basis to ascertain whether the system is continuing to function at peak capacity. Once final emplacement and/or installation of the system has been accomplished, it is then necessary to finish plumbing the system into the hot water supply of the home, office, or establishment in question. This step should necessarily wait until last; however, it is necessary to be fully aware and cognizant of where all of the piping will need to run, where it will tie into the main lines and how the transfer from the system to the end user will take place. Naturally, the individual will need to be mindful of the fact that dependent upon the level of building codes that might exist within the given jurisdiction it may be necessary to have the plans or final product reviewed by a licensed builder or official in order to receive final approval for such a project. In short, the preceding analysis has integrated a basic understanding of some of the instructions for application and installation of a thermosiphon. Such a system is a relatively inexpensive means of creating hot water without having to rely on the conventional means that continue to increase in price each and every year. Moreover, due to the lack of moving components within the systems, once they are in place and fully set up, there is little risk, barring an act of God, that much if anything will go wrong with them. This is of course quite different from a traditional hot water heater which typically needs to be replaced between every 8-15 years time due to decay, old age, or component failure. Additionally, such a system offers to benefits of being able to provide hot water off the grid, being environmentally conscious and friendly, and being greatly more efficient. Some disadvantages therefore necessarily include the fact of the high cost of initial purchase and installation, the difficulty of installing the vacuum tubes so as to avoid any bubble blocks, and a limited amount of hot water generated during a specific period of time. However, notwithstanding, the technology is a promising means by which one can seek to become more self sufficient and provide a net positive effect on the environment and the efficiency of one’s own residence and/or business with respect to energy dependence. Bibliography Mark Song, et al. "A Framework for Photovoltaic and Thermosiphon Systems." International Journal Of Photoenergy (January 2011): 1-9. Academic Search Complete, EBSCOhost (accessed March 14, 2013). Read More