FIELD OF INVENTION
This invention relates to a fresh air ventilation system.
PRIOR ART
In certain metropolitan areas the passenger density onboard commuter trains is extremely high (,, super dense crush load", e.g. in Bombay: 16 passengers per square meter). Even if doors and windows are kept open, the supply of fresh air to the passenger area is insufficient. As a result, the concentration of carbon dioxide in the breathable air rises fast to an unacceptable and potentially harmful level. If doors and windows are closed (for safety reasons and weather protection), the CO2 concentration becomes dangerously high. In order to eliminate this health risk, a sufficient quantity of fresh air is required to be supplied into the passenger area and distributed evenly while displacing the polluted (i.e. CO2 laden) air.
In some urban and suburban areas, the passenger density in commuter coaches, can be extremely high and the quality of the breathable air becomes an important factor for comfort and health. Rail passengers produce carbon dioxide, water vapour and other contaminants including particulate matter, body odours and volatile organic compounds. Excessive carbon dioxide concentrations have a toxic effect. If no fresh air is supplied to the passenger area, the concentration of carbon dioxide in the air will rise fast and exceed accepted safe limits. An insufficient supply of fresh air also causes passenger dissatisfaction.
Conventional commuter coaches do not provide a controlled supply of fresh air. Some amount of fresh air enters the saloon through open doors and windows or when passengers alight at the stations. However, during peak hours, the passenger load obstructs the air flow through doors and windows. In addition, doors are supposed to be closed while the train moves, and windows may also be closed under adverse weather conditions.
Air conditioned rail coaches provide a controlled flow of fresh air to the passenger area. However, if the passenger density is extremely high or the budget for investment and operating cost is limited, air conditioning frequently does not render technically and economically viable.
If the amount of fresh air is high enough, the
• Concentration of carbon dioxide will not exceed a safe level AND
• Bi-effluents (body odours) will be diluted to an extent that most passengers feel comfortable.
Currently used air conditioned metro coaches provide a moderate supply of fresh air while doors and windows are hermetically sealed.
However, it is associated with several disadvantages, which are listed hereinbelow:
1. High initial cost.
2. High operating cost.
3. The unparalled passenger load requirement of many suburban trains can't be met with air conditioned rolling stock.
The above mentioned drawbacks give rise to requirement of a fresh air ventilation system particularly for metro railway applications in densely populated areas.
OBJECTS OF THE INVENTION
The primary object of the present invention is to provide a fresh air ventilation system which overcomes disadvantages associated with the prior art.
Another object of the present invention is to provide a fresh air ventilation system which is efficient and effective.
STATEMENT OF INVENTION
According to this invention there is provided a fresh air ventilation system comprising of ventilation units provided in upper portion of rail car so as to admit fresh air into air duct under ceiling fitted with air diffusers, exhaust openings and a switch gear system.
SUMMARY OF THE INVENTION
The invention is described hereinbelow, which may be taken as an exemplary embodiment without restricting scope of the invention to the same.
According to this invention there is provided a fresh air ventilation system comprising of ventilation units provided with filter positioned in upper portion of the rail car so as to admit fresh air into air duct provided under ceiling and connected to an air handling unit at both ends; fresh air diffuser grills disposed at bottom side of the duct and exhaust grills are located in doors and side walls/windows, and a switch gear system.
Ventilation units are fitted to the end walls of the rail coach or, in case the end wall is not accessible then it is located in a roof well above the passenger compartment.
The ambient fresh air from the ventilation units passes through a cleanable filter. Further, the ventilation unit is provided with atleast one motor/blower unit so as to feed fresh air from outside into the air duct. In case one blower fails then other blower maintains a sufficient flow of fresh air. The ventilation unit is very compact and having protection against rain water.
The fresh air duct runs inside the rail coach under the ceiling. At both ends, the duct is connected to an air handling unit. The duct is partitioned in such a way that, each air handling unit discharges fresh air over the entire length of the rail coach. Even if one AHU/ventilation unit is switched off (at reduced passenger load) or completely fails to operate, the 2nd AHU distributes fresh air evenly over the length of the passenger area.
Further, luminaires, loudspeakers and similar equipment can be accommodated alongside the air duct.
The fresh air diffuser grilles are arranged at the bottom side of the duct and exhaust grilles are located in the doors and side walls/windows. In this manner, a continuous flow of air from the centre (i.e. Duct) to the sides (i.e. side walls) is ensured so that the entire passenger area is evenly ventilated.
The location of diffuser and spacing between diffusers matches passenger density. In the doorway areas, the passenger density reaches its maximum, and the distance between diffusers is reduced in order to provide a constant fresh air flow rate per passenger.
The ventilation system of the present invention can not only be installed in new coaches, but it can also be retrofitted to existing rolling stock.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:
Fig. 1 is a side view of a typical ventilation system arrangement in a non-driving trailer coach.
Fig. 2 is a side view of a typical ventilation system arrangement in a driver coach showing one ventilation unit fitted in a cavity of the coach roof while another ventilation unit is fitted to the end wall.
Fig. 3 is a side view of a typical ventilation system arrangement in a motor coach showing one ventilation unit fitted in a cavity of the coach roof while another ventilation unit is fitted to the end wall.
Fig. 4 is a view of the coach end wall fitted with the ventilation unit
Fig. 5 is a transverse sectional view of the saloon fitted with the fresh air duct and air diffusers
Fig, 6 is a plan of the system layout
Fig. 7 is a sectional side view similar to Fig. 1 illustrating the arrangement of ventilation unit and duct
Fig. 8 is top view, similar to Fig. 6, illustrating the arrangement of centrifugal fans and motors in the ventilation unit.
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS:
The ventilation system of the present invention comprises ventilation units, a fresh air duct fitted, with air diffusers and an arrangement of exhaust openings. The ventilation units draw fresh ambient air and feed
it into the duct extending over the length of the passenger area. The fresh air is discharged into the saloon through the air diffusers located in the duct perimeter. Polluted air leaves the coach through exhaust openings.
Reference may be made to the accompanying drawings.
As seen in Fig. 1, a trailer coach is typically fitted with ventilation units (1) at both end walls. The fresh air duct (2) extends between the ventilation units. The fresh air is discharged into the saloon through openings in the fresh air duct fitted with air diffusers (3).
In case of a driver's cab, the ventilation unit cannot be fitted to the end wall. Therefore, it is located in a cavity of the coach roof and connected to the saloon with an auxiliary duct (6) as shown in Fig. 2. As seen in Fig. 3, a similar arrangement is used where as in the case of the technical compartment of a motor coach, the fresh air duct cannot run through a certain longitudinal section of the coach.
As indicated in Figs. 1...3, exhaust openings are provided in the doors, walls or windows to allow a flow of polluted air, equivalent to the supply of fresh air, to escape.
Now, reference may be made to Figs. 7 and 8 in which the ventilation unit comprises air moving devices/fans/blowers (10) driven by electric motors (11). This provision pushes outside filtered fresh air through duct (s) inside a passenger coach to provide oxygen to dilute Carbon Dioxide produced by humans to bring the level of CO2 to safe level for health and
safety of passengers. At the inlet side of the ventilation unit, a filter or air screen (9) is provided in order to prevent foreign particles entering the fresh air duct.
Referring to Figs. 5 and 6, the fresh air duct extends between the ventilation units across the length of the passenger area. It is advantageously partitioned (7) to ensure a constant air pressure and an even distribution of fresh air over the duct length. The spacing between the air diffusers (3), or the diffuser size, can be selected to control the flow rate of fresh air. In this manner, coach sections with a particularly high passenger density, such as the doorway zones, can receive an increased flow of fresh air.
Further, extra air circulatory devices/fans may be provided inside coach to enhance comfort level of passengers in hot weather.
In order to minimise the operating costs of the fresh air ventilation system, the flow rate can be adjusted in accordance with the actual passenger load. Further, in order to reduce the flow rate, one of the two ventilation units (1) can be switched off during off-peak periods. As an alternative, one or more air moving devices /fans/ blowers units (10)(11) can be switched off. Further alternatively, the fan speed can be reduced.
For optimum passenger comfort, both the supply of fresh air and the air velocity in the passenger area are required to be controlled. While the air velocity should generally be low in air conditioned coaches maintaining a defined climate, a much higher air velocity is desirable in a hot
environment if no air conditioning is provided. For this purpose, the fresh air ventilation system is assisted by an arrangement of air circulation fans (8) as seen in Figs. 5 and 6.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-

WE CLAIM;
1. A fresh air ventilation system comprising of ventilation units provided in upper portion of rail car so as to admit fresh air into air duct under ceiling fitted with air diffusers exhaust, openings and a switch gear system.
2. A fresh air ventilation system as claimed in claim 1 wherein said ventilation units are provided with filter at the inlet side so as to prevent foreign particles entering the fresh air duct.
3. A fresh air ventilation system as claimed in claim 1 or 2 wherein said exhaust openings are provided in the doors, walls or windows to allow outflow of polluted air.
4. A fresh air ventilation system as claimed in any of the preceding claims wherein said ventilation unit comprises air moving devices/fans/blowers driven by electric motors.
5. A fresh air ventilation system as claimed in any of the preceding claims comprising of a plurality of air circulation fans such as herein described.
6. A fresh air ventilation system as claimed in any of the preceding claims wherein said duct is connected to an air handling unit at both ends.
7. A fresh air ventilation system as claimed in any of the preceding claims wherein said ventilation units are fitted to the end walls of the rail coach or, in case the end wall is not accessible then it is located in a roof such as herein described.
8. A fresh air ventilation system as claimed in any of the preceding claims wherein luminaries, loudspeakers and similar equipment can be accommodated along side the air duct.
9. A fresh air ventilation system substantially as herein described with reference to the accompanying drawings.