Thermal energy is required in a high range of temperature in many industrial processes. Solar thermal systems are of great use for this kind of thermal processes. Using solar heat into a wide variety of industrial processes has been a challenging work. About 70% of the annual load is usually produced by such a system.
Solar water heating systems are of great use & moreover is mainly designed to minimize life-cycle cost but depends upon the rays of the sun. Maintenance, freeze protection, overheating protection, aesthetics of the collector mount, and orientation can be considered as the other considerations for solar water heating systems other than the sun’s rays.
WHILE DESIGNING A SOLAR HOT WATER SYSTEM FOLLOWING THINGS ARE REQUIRED:
Solar hot water system consists of tanks. A well-insulated storage tank is needed for most of the solar hot water tanks. Converted electric water heater tanks are used by many systems for storage or plumbing a conventional water heater in series with the solar storage tank.Collectors are one of the must needed things for designing solar hot water systems.
Collectors are of different types, but the flat-plate collector is the most commonly used collector. It is an insulated, weatherproof box, made of metal or plastic, containing a dark absorber plate beneath a translucent cover. There are Plastic collectors too, but Metal collectors are more sturdy, fire-resistant, and expensive to manufacture than plastic collectors.
Another critical component while designing a solar hot water system is the Control & Circulator. The control & the circulator both work in a series with each other. As the collectors get warmer than the tank, the control turns on a circulator that circulates a heat transfer fluid, which is water or a water-glycol mixture, through the collectors and back to the heat exchanger located in or adjacent to the storage tank.Solar hot water systems are incomplete without another important part that is the Heat Exchanger. It has an important function of transferring heat from the heat-transfer fluid to the household water supply.
The solar collectors should be located properly because they are used for heating both space and water, although space heating requires a much greater collector area and storage capacity. It should be rotated 30° towards the true (not magnetic) south. All the year-round the solar gains maximizes by equalizing the tilt angle to the geographical latitude. Rising of the collectors flushes on a pitched roof close to the optimal orientation.
These are the preventive measures that should be followed while designing solar hot water system:
PROTECT AGAINST FREEZING
The collector flow passages are very effective parts of the system & if water freezes inside it, it can cause considerable damages. But this damage can be prevented by some methods that are given below:
The most typical process is to use a solution of propylene glycol and water to circulate in the system in the collector loop of an indirect system.
Another process is to draw off the water from the collector back into a small drain-back tank. This has an added advantage of protecting the system from excessive temperatures if hot water consumption is reduced due to seasonal use patterns, remodeling, or vacations.
PROVIDE A TEMPERING VALVE AND SIDESTEP CAPABILITY
The tempering valve helps to maintain a consistent temperature of water. Sidestep piping and valves are of great use as they allow the conventional system to provide hot water when the solar heating system is down for any reason.
PROVIDE PERIODIC MAINTENANCE FOR ALL SYSTEMS
The maintenance should be done on a regular basis for the well conditioning of the system such as: checking the pH and freezing point of heat transfer fluid, checking proper pump operation, etc.