Standards Development

Scope

This document applies only to Dimethyl Ether refuelling connectors with pressure equalizing port hereinafter referred to as devices, constructed entirely of new, unused parts and materials. Dimethyl Ether refuelling connectors with pressure equalizing port consist of the following components, as applicable:

a) Nozzle with pressure equalizing port

Refuelling nozzle and pressure equalizing port are integrated so that opening and closing of refuelling path and pressure equalizing path can be performed simultaneously (mounted on dispenser side) (see Clause 5) .

b) Receptacle with pressure equalizing port (mounted on vehicle) (see Clause 7)

This document applies to devices which are for Dimethyl Ether as fuel, hereinafter referred to in this document as M15(see 9.1c):

This document applies to devices with standardised mating components.

This document applies to connectors which prevent Dimethyl Ether vehicles from being fuelled by fuel station dispensers for other gaseous fuels

This document is applicable to: Dimethyl Ether in accordance with ISO 16861. DME Refueling Connector specified in this document shall be connected and used with a dispenser conforming to OIML Recommendation R 117-1.

All references to pressures (kPa) throughout this document are considered gauge pressures unless otherwise specified.

Purpose

This proposal is a DME refuelling connector for the same purpose as DME refuelling connector (ISO/DIS 21058), but the filling method is different.

ISO/DIS 21058 is a pressurization filling type connector similar to LPG refuelling connector (ISO19825) for LPG vehicles, and this proposal is a pressure equalization filling type connector.

1) Functional requirements for DME filling

DME vehicle has a diesel engine with excellent environmental performance, and is especially expected as medium and heavy duty trucks. Large-capacity fuel tank is required from the viewpoint of heat value, and the filling amount is larger than that of diesel fuel. It is socially unacceptable for longer filling time. Therefore, rapid filling speed with two or three times of LPG filling is necessary.

2) Increase in internal pressure of fuel tank for DME filling In the fuel supply system of diesel engine vehicles, the fuel tank temperature rises due to the return fuel from the engine to the fuel tank, and the tank internal pressure also rises. The internal pressure of the tank after driving is affected by ambient temperature, load conditions, remaining tank capacity, fuel supply system characteristics, road surface conditions, etc. Especially the internal pressure of the tank becomes high especially in summer and high temperature areas.

3) Problems of pressurization filling method

The problem is DME rapid filling is not possible with the pressurization filling method. In the DME pressurization filling to the fuel tank in state of previous paragraph, it is necessary to use a high discharge differential pressure pump. However when ambient temperature is high, rapid filling may not be possible even with a high discharge differential pressure pump that is currently in practical use, based on data from DME vehicles that have been tested so far. In addition, there is a problem that pressurization filling type dispenser with two hoses cannot fill DME to two DME vehicles rapidly at the same time regardless of the season.

4) Contents of pressure equalization filling method

4-1; The pressure equalization filling method connects the vehicle fuel tank and the station storage tank with a pressure equalization hose before filling, and equalizes both pressures so that a constant flow rate can be charged by a low differential pressure pump regardless of the fuel tank internal pressure before filling. This is a method that enables DME rapid filling regardless of ambient temperature.

4-2; Although the OIML recommendation, the international standard of legal metrology, does not allow the application of pressure equalization filling method to LPG filling, but allow DME filling. This is because LPG is a mixture of propane and butane, and LPG with different mixing ratios is commonly distributed, so there are problems in mixing ratio change due to pressure equalization and the appropriate correction of the measurement value due to pressure equalization. Whereas DME is a single molecule. In this case, no problem with mixing ratio, and appropriate correction method by measurement of the return flow is also shown in the OIML Recommendation.

4-3; The dual port connectivity and sealability are integrated, and simultaneous connection and disconnection and operability can satisfy almost the same conditions as the requirements and tests of the DME refuelling connector standard (ISO/DIS 21058).

5) Necessity and significance of pressure equalization filling system standardization

5-1; In parallel with the pressurization filling type refuelling connector currently under discussion, standardizing the pressure equalization filling type refuelling connector as another option enables rapid DME filling even in high-temperature areas such as India or in environments with heat waves.

5-2; By standardization of this connector DME vehicles with excellent environmental performance can be introduced and spread all over the world regardless of the region.

5-3; The pressure equalization filling method enables rapid filling even with a low-pressure pump, reducing the station cost.