Welcome & Announcements: Professor John Simmons, Head of Department, welcomed members to the 10th HEXAG meeting. He briefly described some of the heat transfer activities within the Department, and expressed his pleasure at the fact that the Department also hosted the HEXAG Web site.

David Reay, HEXAG Co-ordinator, then ran through a series of announcements of interest to members:

Technical Presentations: Peter Kew 'kicked off' by presenting some ideas on miniaturisation of thermal machinery. He said that reducing size was a very good think from the point of view of heat transfer, showing that small hydraulic diameters lead to higher heat transfer coefficients and HTC/unit volume. Citing the example of a package boiler, the size can be easily reduced by 50% using smaller diameter tubes. Problems which might arise are fouling (which can be overcome); manufacturing technology (which exists), and pressure drop (we can make short fat designs). The headers can become as large as the heat transfer volume, however.

With regard to power transmission (e.g. compressors, turbines) Peter showed that the speed needed to increase a lot as size reduces, to maintain or increase power output. While a HX can shrink but have an increased rating, a smaller work machine will have to be reduced in rating. There were examples where difficulties caused by this could be overcome by good design, e.g. the Glynwed Rankine-Rankine heat pump and the MIT micro-gas turbine (50We using a 4 mm diameter turbine with 1 gm weight). Peter proposed the concept of using the block of, for example, a PCHE as the compressor housing, as well as the evaporator and condenser of a 10 kW refrigerator package. This could eliminate pipework and even use the headers as housings. Integration of the work machine with CHEs was the main message. Contact: Dr. Peter Kew, tel: 0131 449 5111 ext. 4344; fax; 0131 451 3129.

Hans Zettler, a member of Prof. Hans Müller-Steinhagen's group at Surrey, talked about their work on fouling in PHEs. Experimental work was backed up by CFD, looking at the flow distribution in 3-D channels. CaSO4 solutions with various concentrations were used in experiments, giving crystallisation fouling without any particles. The effect of solution flow velocity on fouling was examined, as was solution concentration. Different plate designs had significant different fouling performances. Those of one manufacturer performed better than another supplier's under clean conditions, while the position was reversed in fouled streams. The effect of distributor design was also examined. Changes to gaskets avoided recirculation and led to more even temperature distributions. Sanding of the flat plates used in these later tests had a positive effect. Surrey is now proposing to examine the effect of corrugation angle on fouling, and proposes surface-modified plates in this context. Contact: Dr. Hans Zettler, fax: 01483 259239.

Trevor Hodgkiess from Glasgow University and partners at Heriot-Watt discussed scaling, as part of a corrosion and surface engineering project. It started as an assessment of electrochemical methods for studying biofouling, but was found to be more appropriate to mineral scale deposition. The novelty was in the ways of studying scale growth. This led to the ability to use electrochemical techniques for measuring the efficiency of scale inhibitors (such as PPCA). A good correlation was found between the electrochemical method and image analysis work, and measurements on tap water, heated to induce scale, demonstrated the effectiveness of inhibitors. Contacts: Dr. Trevor Hodgkiess, (see attendance list), Dr. Anne Neville, tel: 0131 449 5111; fax: 0131 451 3129.

Continuing in the same areas, Norman Glen of NEL introduced a proposed project on 'sustainable industrial water use', directed at reducing the impact of industrial water use on UK resources. The DTI is being invited to fund work examining the implications of using 'appropriate quality' water - water not over-treated for the duty it is used for. In industry, 38% of water used there passes through heat exchangers, amounting to 2040 Megalitres/day. It is believed that 'appropriate water' use could lead to a 20% reduction in industrial use of potable (treated to drinking water standards) water. This would relieve pressure on domestic use, which is expected to rise by 0.5% per annum. There are few water monitors on industrial plant, and a lack of confidence in lab. Experiments on less pure water when scaled up to plant size.

An essential component of the proposed study will be the PFAU - portable fouling assessment unit - from NEL, which can monitor side streams, and one aim is to show that point measurements can be representative of what is happening in the whole heat exchanger. After outlining the proposed project, Norman said that there would be a steering group to monitor progress, advise on industrial practice, and assist in dissemination. If you are interested, contact: Norman Glen, fax: 01355 272536.

Support Programmes: Fiona Porter, responsible for process technologies, including CHEs, at ETSU, outlined the Energy Efficiency Best Practice Programme and ways in which it will improve energy efficiency. CHEs had been estimated to give savings of £10 million p.a. Current projects included heat exchanger-reactors (BHR Group), tube insetts to reduce fouling (Cal-Gavin) and a polymer heat exchanger (Newcastle University). Contact: Fiona Porter, tel: 01235 433012, fax: 01235 433727, Email: Fiona.Porter@aeat.co.uk.

Tom Ralston of NEL then reported on progress on the 'linking within Europe' HEXAG activity. 81 companies who were HTFS members had been mailed, in 8 countries. 23 had responded and several had been added to the HEXAG membership. These are seen as potential partners for the next EU framework programme, and appropriate data will be included in the HEXAG Web Page.

David Reay reported on progress towards FPV. It seems that calls for proposals could be issued in the period January-March 1999. HEXAG members can access the appropriate Web site for regular updates - see attached sheet 'Fifth Framework Focus'. John Sillwood, who spoke at the previous HEXAG meeting, had written stating that NPL BRITE-EURAM Helpline was offering a booklet, including case studies and comments of programme participants - tel. 0181 943 6660 (Note - this corrects the number given out at Heriot-Watt).

Impromptu presentations: These covered topics ranging from the 1999 UK National Heat Transfer Conference (at Heriot-Watt) - contact IMechE or Prof. Keith Cornwell at Heriot-Watt; anti-fouling work in Japan in PHEs and PFHEs - contact David Reay; new low fouling surfaces leading to 99% reduction in fouling - contact Hans Zettler, (see above) the protection of shells from over pressure in S&T hx's - contact Derek Wilson (see attendance list), and an initiative to establish a thematic network on process intensification - contact Prof. Colin Ramshaw (see attendance list).

Tours were made to several of the heat transfer laboratories within the Department. Information on the work undertaken is given in the attachments.

NEXT ISSUE OF HEXAG NEWS - OCTOBER 1998. Articles to David Reay, please.
















Colin Adderley, Rolls-Royce plc. Fax: 01332 622948

Tom Bruce, Edinburgh University

Chiu Kee Cheung, BHR Group Ltd. Fax: 01234 750074

Keith Cliffe, Chem. & Process Engng., Sheffield University. Fax: 0114 222 7501

Keith Cornwell, Heriot-Watt University.

Grant Cuthbertson, Heriot-Watt University. Fax: 0131 451 3129

Eric Ferguson, GEC Marconi Avionics. Fax: 0131 343 4091

Bill Fletcher, Consulting Engineer. Fax: 01978 852118

Norman Glen, NEL. Fax: 01355 272536

Terry Heppenstall, The Pipe Dream Company. Fax: 0191 2961798

Trevor Hodgkiess, Mech. Engng., Glasgow University.

Andrew Jenkins, NEL. Fax: 01355 272536

Roshan Jachuck, Newcastle University. Fax: 0191 222 5292

Tassos Karayiannis, South Bank University. Fax: 0171 815 7699

Peter Kew, Heriot-Watt University. Fax: 0131 451 3129

Song Lin, Heriot-Watt University. Fax: 0131 451 3129

Alick MacGillivray, NEL. Fax: 01355 263398

Mike McLean, Brown Fintube. Fax: 01258 840961

David McNeil, Heriot-Watt University. Fax: 0131 451 3129

Robin Merchant, Serck Heat Transfer. Fax: 0121 766 6014

Keith Miller, Heriot-Watt University. Fax: 0131 451 3129

Arnaud Morizot, Heriot-Watt University. Fax: 0131 451 3129

Anne Neville, Heriot-Watt University. Fax: 0131 451 3129

Fiona Porter, ETSU. Fax: 01235 433727

Simon Pugh, ESDU International plc. Fax: 0171 490 2701

Tom Ralston, NEL. Fax: 01355 263398

Colin Ramshaw, Chem. Engng., Newcastle University. Fax: 0191 222 5292

David Reay, David Reay & Associates. Fax: 0191 252 2229

Gordon Rowe, Serck Heat Transfer. Fax: 0121 766 6014

Kays Tayeb, Baz Engineering Services. Fax: 0181 949 1450

John Simmons, Heriot-Watt University.

Derek Wilson, MW Kellogg Ltd. Fax: 0181 872 7272

Hans Zettler, University of Surrey. Fax: 01483 259239