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Saving water in showers

Saving water in showers. Sponsored by United Utilities and involving a team of JMU staff from four schools: BMS, BLT, ENR and the Business School. United Utilities staff:. Dr Richard Critchley. JMU staff:. Dr David Phipps , BMS Dr Rafid Al-Khaddar, BLT

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Saving water in showers

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  1. Saving water in showers Sponsored by United Utilities and involving a team of JMU staff from four schools: BMS, BLT, ENR and the Business School

  2. United Utilities staff: • Dr Richard Critchley

  3. JMU staff: • Dr David Phipps , BMS • Dr Rafid Al-Khaddar, BLT • Dr Robert McClelland, Business School • Dr Robert Doherty, Business School • Prof Roger Morgan, Engineering • Ms Kirsty Barr, Enterprise

  4. JMU Project Officers • Mr Benoit Karci • Mr Julien Hordesseaux

  5. Why is the project needed? 1980s government removed regional subsidies • Uncontrolled increase in industrial activity in south Large shift of population to South-East of England • High density of population • Dry climate • The South-East is short of water

  6. Typical water consumption Figures from Ofwat (www.ofwat.gov.uk) • Typical shower uses 35 litres • Typical bath uses 80 litres • Loo flush uses 7.5 to 9.5 litres • Hosepipe (banned in SE) uses 540 litres per hour

  7. Shower types Showers come in different sorts - • Electric shower 2 to 3 litres per minute • Shower from hot water supply 5 to 6 litres per minute • ‘Power shower’ 10 to 12 litres per minute • Showering time 3 to 10 minutes So a shower can use more water than a bath!

  8. What is a ‘good shower’? Focus group priorities: (independent of age, gender, meter status, etc) Constancy of temperature Temperature distribution Volume of water Distribution of water Skin pressure

  9. Experimental rig 1 Conventional shower cubicle Exchangeable mixer valve Exchangeable shower heads Measurements of flow, pressures, temperature, skin pressure

  10. Experimental rig 2 Pumps with separate hot and cold flows Same motor, same shaft ‘Power shower’

  11. Typical head

  12. Water flow vs supply pressure Experiments on different shower heads Head 3 has adjustable setting For turbulent flow expect square law Experimental results agree accurately with theory

  13. Water flow vs supply pressure Might expect relationship between total hole area and flow at given pressure Experimental results indicate only a weak relationship This needs further work

  14. Water distribution 1

  15. Water distribution 2

  16. Water distribution results Ideally we want flow distribution independent of flow rate .. Some heads are better than others Good – constant distribution Bad – distribution changes

  17. Skin pressure 1 Used to be commercially available Used in GERI-atric nursing No longer available

  18. Skin pressure 2 Use standard electronic manometer Add diaphragm on thistle funnel Equilibrate temperature Close system and put under shower Measure pressure increase Can be calibrated absolutely

  19. Skin pressure results Plot of skin pressure vs flow rate Skin pressure goes up as square of flow So you can get a vigorous shower without too much extra water But you can’t save much water without getting a piddling shower

  20. The head factor Pressure ratio across the head is approximately constant

  21. And now what? • Try out various shower heads and modifications in people’s houses!

  22. That’s all, folks ..

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