The rail to hell

Anyone unfortunate enough to be on a train from Tottenham Hale to Victoria last week would agree that Dante’s inferno would be a picnic by comparison. The saunas in Victoria can’t have been doing much business either – we’d all had one long before we arrived!

So I was as relieved as anyone to learn that at long last the London Underground is to be air conditioned. Initially just the above ground and sub surface lines – but they are also committed to cooling the deep lines too.

This brings back memories of the Channel Tunnel cooling project – initially very innovative, with the finless cooling tubes relying on rammed air from the passing trains, but spoilt by the inept use of air cooled R22 chillers rather than marine cooled ammonia screw chillers.

Is history going to repeat itself? The deep tunnels and stations will be cooled by the highly innovative use of ground water – but the specification for the trains calls for HFC R134A or R407c. Surely the F-Gas directive will be extended to trains before this project is complete? If so what to use? Flammables including R1234 won’t be allowed underground. R744 would probably pass toxicity tests, but what about a condenser failing at 130 bar pressure in a confined space? There may be an engineered answer, but I’ve seen a more elegant solution.

Air cycle cooling is used in Germany’s ICE-2 high speed trains, with lower overall life cycle costs than conventional HFCs systems. In the event of failure, the worst case scenario is air leaking into the passenger compartment – the hazard study shouldn’t take long for that one.

And like hell, it exists, I know because I’ve seen it!

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