DESIGN OF A RAILWAY COACH SOLAR HEATER AND PUMP SYSTEM
Chapter 2 1
Literature Review 1
1. Introduction 1
2. History of Solar Water Heating 1
3. Technical Analysis 2
4. Pump selection 5
This chapter includes history of Solar Water Heating and the technical analysis of the latest technology in Solar Water Heating systems. The analysis of the latest technology involves all aspects of Alternative Solar Water Heating systems design. Low cost alternative water heating system for the train coach, direct versus indirect systems, components and materials used was investigated.
2. History of Solar Water Heating
Solar water heating has been around for many years because it is the easiest way to use the sun to save energy and money (Lewis, 2005). The first solar water heater that resembles the concept still in use today was a metal tank that was painted black and placed on the roof where it was tilted toward the sun (Cromer, et al., 2006). The concept worked, but it usually took all day for the water to heat, then, as soon as the sun went down, it cooled off quickly because the tank was not insulated (Cromer, et al., 2006). In some rural areas, the olden method of water heating through sun is still practiced, where water is poured into a plastic basin and placed on the sun through the day.
For this project, the solar water heating system for the train coach will be the first of its kind as the shape will be following the roof curvature.
3. Technical Analysis
3.1. Basics of Solar Heating Systems for the train coach
Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: Active and passive: pumps and controls are on active systems and not on passive systems. A well-insulated storage tank is required in most systems and in a two-tank system; the solar water heater preheats water before entering the water heater. In one-tank system, the backup heater (geyser) is combined with the solar storage in one tank.
3.2. Direct against Indirect Solar Water Heating Systems
Direct systems consist of one or more solar panels. Water is pumped into solar panels where it is directly heated by the sun and then pumped into storage tanks where it is stored. Direct systems are very effective but have a shorter life span when compared to indirect systems. The reason being is that, the water chemicals erode the pipes and the panels over time and hence have to be maintained regularly. Water inside the panels can freeze in colder weather conditions which may result in damaging the system (Choosing a solar geyser, 2010).
Figure 1-Direct System
Advantages of a Direct System
Service water used directly from collector loop
No heat exchanger – more efficient heat transfer to storage
Circulation pump needs only to overcome frictional losses.
Disadvantages of a Direct System
It is only convenient to use them in...