Ventilation control (in new stock)

evaluated

Traction equipment is cooled by ventilation to prevent over-heating. The energy needed for ventilation can be substantially reduced by demand-controlled operation, i.e. by controlling ventilation power (e.g. the speed of the mechanical fans) according to actual cooling demand of the motor (or other traction equipment). The technology is wide-spread but not a standard yet.

Technology field: Optimisation of traction technologies

General information

Description

Conversion losses of traction equipment of an electric traction unit show up as heat that must be removed from the system continuously to prevent over-heating. This is done by the coolers that in many locomotives are realised as mechanical ventilators. Although at peak load the power required for cooling is almost negligible, it is not at low load (cf. Figure 1). This share can be substantially reduced by demand-controlled operation, i.e. by controlling ventilation power (e.g. the speed of the mechanical fans) according to actual cooling demand of the motor (or other traction equipment). While most modern locomotives and some EMUs are equipped with demand-controlled ventilation, the technology does not seem to be a standard in new stock. Old stock can in some cases be equipped with demand-operated ventilation as a retrofit.

General criteria

Status of development: in use

In locomotives, demand-controlled ventilation is becoming a standard (including high speed trains, such as TGV).

Time horizon for broad application: now

(no details available)

Expected technological development: basically exploited

The main barrier for a wide-spread use of demand-controlled ventilation in EMUs lies in the fact that a demand-control would mean variability of the whole board-supply including other equipment such as batteries etc. There could be minor technological potential for solving this problem.

Motivation:

Energy saving
Noise reduction in stations

Benefits (other than environmental): medium

Noise reduction

When leaving a station, coolers make a high contribution to train noise. This can be substantially reduced by demand-control.

Barriers: medium

Technological

Most coolers use (frequency-controlled) 3-phase motors. Their speed is controlled by the frequency of the board energy supply. Other equipment (batteries etc.) supplied by the on-board grid, would then be strongly affected as well. In this case a demand-control of ventilation would require a separate frequency-variable energy supply, which is raises costs and complexity. This is especially a problem for EMUs having a very complex on-board grid. Even if separate inverter equipment is needed, LCC are still in favour of demand-operated ventilation. However, in most cases manufacturers will not implement a measure that raises the price of the vehicle even if it reduces LCC.

Vibrational issues

Variable frequencies due to demand-controlled fans may cause vibrational problems (resonant behaviour of train components). This problem has been resolved according to SNCF.

Success factors:

Integrate demand-operated ventilation in specification sheet for locomotives.
Integrate separate account for auxiliaries' consumption into energy efficiency specification given by manufacturers

Applicability for railway segments: (no data)

Type of traction: electric - DC, electric - AC, diesel

Type of transportation: passenger - main lines, passenger - high speed, passenger - regional lines, passenger - suburban lines, freight

(no details available)

Grade of diffusion into railway markets:

Diffusion into relevant segment of fleet: (no data)

Share of newly purchased stock: (no data)

(no details available)

Market potential (railways): high

(no details available)

Example:

(no details available)

Environmental criteria

Impacts on energy efficiency:

Energy efficiency potential for single vehicle: 2 - 5%

Energy efficiency potential throughout fleet: (no data)

The energy savings strongly depend on the point of reference chosen. Compared to old locomotives the potential is higher than compared to modern stock. The experience with retrofit projects in Switzerland, Austria and Russia demonstrate that in extreme cases (freight trains on certain routes) the savings can amount to 5 % and more. Usually they will be lower.

Figure 1 shows the relation between tractive power and the auxiliary power expressed as a percentage for the case of fixed ventilation (no demand-controlled operation).

Figure 1: Relationship expressed in percentage terms between the auxiliary power and real-time tractive power using the example of a 5 MW traction unit.

Source: IZT, data from Slattenschek 2000

Other environmental impacts: neutral

(no details available)

Economic criteria

Vehicle - fix costs: (no data)

For new stock the price of frequency-variable ventilation and demand-controlled operation is difficult to determine, since the technology is part of the train/locomotive design.

Vehicle - running costs: significant reduction

(no details available)

Infrastructure - fix costs: none

(no details available)

Infrastructure - running costs: unchanged

(no details available)

Scale effects: low

(no details available)

Amortisation: (no data)

(no details available)

Application outside railway sector (this technology is railway specific)

Overall rating

Overall potential: very promising

Time horizon: short-term

Demand-operated ventilation is a feature of many but not all modern electric vehicles. In MU stock the main obstacle is additional cost and complexity due to the required separate auxiliary inverter. However, LCC are likely to be in favour of demand-operated ventilation even in MUs.

References / Links: Bänziger et al. 1995; Mouginstein, Pokrovskij 2000; Slattenschek 1997; Slattenschek 2000

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date created: 2002-10-09