A SAFE SOLUTION FOR TESTING ETHANOL BASED FUELS
Howell, Operations Manager, at EJ Bowman looks at the increasingly
critical role played by heat exchange technology in engine test rig
applications, particularly for ethanol based fuels.
Bowman work with many leading
automotive manufacturers and engineering consultants and in the past few years,
we have seen an increasing trend for our customers to carry out more cycle
simulations on engine test beds, as manufacturers seek to reduce the costs
associated with running prototype vehicles.
However, when trying to simulate
vehicle cycles accurately on a rig, it is essential that the fluid temperatures
and warm-up profiles experienced in prototype vehicle test runs are simulated
precisely on the test bed.
The design of the heat exchanger
itself is critical to achieving the accuracy of the simulation - and stainless
steel in-line ‘plate’ type heat exchangers have become the industry standard
for cooling fuel on automotive test bed engines.
However, the growing introduction of
ethanol into fuels has made new demands on these stainless heat exchangers
which are traditionally brazed with copper materials. In the US,
Environmental Protection Agency (EPA) regulations already allow blended fuel to
contain up to 10 percent ethanol and in February 2012, the US Environmental
Protection Agency decided to pave the way for the sale of gasoline blended with
up to 15 percent ethanol.
systems developers, manufacturers and consultants are carrying out extensive
research on ethanol based fuels to assess their ability to meet increasingly
stringent fuel economy standards and engine performance.
customers based in the US
customers wishing to sell vehicles in the US are testing fuels on test bed
engines that are either 85 to 100% ethanol. The problem is that using ethanol
in fuels, even in modest amounts, can cause copper to be leached into the
ethanol and deposited on to the fuel injection system, with the risk of
performance problems and failures.
To address this issue, Bowman has
developed a new design of heat exchanger which has an iron/chrome brazing
compound, which is believed to be an industry first. The new unit eliminates
copper from the manufacturing process, so there is no risk of it leaching into
the fuel injection system.
The problem with ethanol is that it
attacks the copper and removes any deposits it comes into contact with which can
then be deposited onto the fuel injection system causing fouling and possible
engine damage. Several of our leadingautomotive
customers approached us to try and come up with a solution. Our R&D team
has responded by developing a totally new construction method for our stainless
steel in-line plate heat exchangers.
Heat exchanger design is obviously
focused on the optimal transfer of heat. Bowman favours a design that
dissipates heat efficiently via channelling the fuel around the maximum
internal surface area of the unit.
heat exchangers consist of numerous
316 stainless steel plates, two outer covers and four connections vacuum-brazed
together to form an integral unit. Unlike other plate heat exchangers, they
have a unique internal flow arrangement, which enables the inlet and outlet
connections to be
located in line. This means that they can be installed directly into the fuel
line without the need to modify or re-route the pipework.
Each fluid stream flows in series
through alternate plates. As a consequence, the plate spacing is larger and
internal velocities are higher than is normally the case with this type of heat
exchanger, thus rendering them less prone to fouling.
Normally, the plates are brazed
together via a copper shim. Whilst this traditional way of constructing a plate
type heat exchanger has proved satisfactory up to now, the introduction of
ethanol into vehicle fuels has created a major challenge for the use of copper.
We carried out an extensive research
and development programme into materials that could provide a suitable
alternative to copper. As a result, we have developed a totally new brazing
compound. No copper is used in the manufacturing process, eliminating the
problems experienced previously.
Bowman has implemented extensive
in-house testing to prove the effectiveness of the new brazing compound.
We also had to ensure that the new
copper-free heat exchangers delivered all of the high heat transfer efficiency
customers expect yet are totally safe for ethanol fuels.
The results of initial tests have
proven that the new heat exchanger construction works reliably and efficiently
on Ethanol based fuels, even at 100% levels. We are now putting the new unit
through an intensive testing programme with a respected independent automotive
engine systems specialist to validate our initial findings and provide ‘real
time’ performance and reliability data. The results should be available
Bowman manufacture a comprehensive
range of cooling products for engine test cells, including charge air,
hydraulic and fuel coolers, plus exhaust
gas, header tank, in-line plate type and stainless steel heat exchangers.
more information contact:
Kevin Howell, Operations Manager
E J Bowman (Birmingham)
Chester Street, Birmingham B6 4AP,
T: +44 (0) 121 359 5401.
F: +44 (0) 121 359 7495.