Update on the Vulcanus MK4 Microwave Water Heater

1 Posted 2006-01-07 17:52:40 by Kieran (kieran.kennelly@sympatico.ca)

unfortunately I still cannot get on to Pulsar's website #1 or #2. Dose anybody have a phone # to contact the company ? Thank you.

2 Posted 2006-01-07 18:36:47 by Sean

Kieran, I can get to the site ok now. The site is done entirely in flash, so that might be the issue if you're ending up at a blank page perhaps...
Anyway, the number on their site is 514-931-4745. Maybe they'll provide you with more info than I got when I emailed them, which netted a useless "Thanks for your interest..." response.

3 Posted 2006-01-08 16:31:12 by Sean

I called the number and didn't get an answer (it was a Sunday however, so I wasn't expecting an answer as much as a voicemail/machine, which I didn't get). Strange.

4 Posted 2006-08-25 22:28:34 by chris (grchr@hotmail.com)

these systems are standard issue in japan..maybe good research info here in Japan..

5 Posted 2006-10-16 20:01:06 by Roger (brlong@telusplanet.net)

Any updates as to when this will hit the market? I get no response to e-mails. Have not tried to call.

6 Posted 2006-11-04 13:31:27 by William Tilstra (greendolphin394@msn.com)

Dear Sir or Madam, Conserning Pulsar Vulcanus MK4, I would like to have more information.Please and Thank you.

7 Posted 2006-12-19 00:24:45 by Sandra

ok.... so I should stop dreaming of instant hotwater. I spoke with my plumber and he said, "check it out because they seem to be trying to address the extreme cold ground water here in Northwestern Ontario." Is this Valcanus MK4 for real or do I stop dreaming and put my walls and floors back together. Any input about hot water on demand would be most appreciated.

8 Posted 2006-12-19 21:21:13 by Sean

Hi Sandra. I'd also like to know more about this product but I'm starting to get a little skeptical myself. I emailed for more information last year and got a friendly response. About a month or two ago I emailed Pulsar again looking for an update and have yet to receive a reply. Their website hasn't had any news and has been looking pretty static for quite some time; maybe going on a year now.

9 Posted 2007-02-05 11:10:09 by shirish (shirish_desh@yahoo.co.in)

even i am not sure that product is available because there is no much details.

10 Posted 2007-02-12 10:02:43 by Stephane

HI, I live in mtl, where pulsar is, after a few months I manage to get an answer, they will not sale the product this year (2007) as promised. There were financial or dont remember what problem, so the hope is dead. Maybe in a year.. dunno!
Ciao.

11 Posted 2007-02-12 17:24:00 by Sean

Thanks Stephane, I'm sure a lot of people will be interested to read this news, as disappointing as it may be...

12 Posted 2007-02-19 18:54:35 by vince

can we wire it on former 20 amp?
or higher?

13 Posted 2008-09-18 15:42:02 by TheMan

They are no answer at the phone number, the website is not working yet...

14 Posted 2008-11-09 15:26:28 by Brian (SAUNDERS@rideau.net)

I have been trying for a while to get up to date info on this product. ANY NEWS?

15 Posted 2008-12-25 11:15:49 by George (j.h@sua.com)

I knew this company at least four year with the flash web site .Honestly i am sure they are fake and there is no any product like this at all .Indeed someone would like to fun people

16 Posted 2010-03-24 16:15:55 by SwampYankee

Wanderport has purchased Pulsars technology and appears to be actively working on production and distribution

17 Posted 2010-03-30 06:45:48 by bob

hello

Wanderport just speculate on this technology.

take care, do not buy any stocks from them.

18 Posted 2011-10-20 00:09:57 by cash loans

I also have noticed that this he
first model has the capabilities
to go from 35F-140F within
seconds and supply multiple
outlets concurrently. That's
really amazing.

19 Posted 2011-10-25 21:48:08 by Fake Watch

The light is not random, but made up of the effects of scene changes

20 Posted 2011-11-09 21:53:28 by wedding dresses

That's great idea. it will help us a a lot. Thanks!

21 Posted 2011-11-28 18:56:29 by JBGibson

« It really is a Good Friday | Main |
Michael Pollan, NPR, and biodiversity »

Tankless microwave water heater:
energy cost

A few weeks ago, a company called
Pulsar Advanced Technologies
announced that they had developed a
microwave-powered tankless hot
water heater. The idea is an intriguing
one: rather than maintaining and
heating a 50-gallon tank of water
24/7, simply replace the tank and
heater with a microwave-powered unit.
When the unit detects a pressure drop,
it powers up the magnetron and
rapidly pumps microwaves into the
passing water. The virtue of the
tankless water heater is that it doesn't
require constant thermal regulation of
a large tank—the microwaves simply
heat the water when needed. And the
assumption, at least, is that microwave
heating of water is relatively efficient
and fast enough to fully heat the water
as it flows through the unit.

Is it such a far-fetched idea? One
reader at Slashdot named Lawrence
Wade (a.k.a. "BigBlockMopar") opines:

"Consider, for a second, that most
microwave ovens put out something
on the order of 700W of RF power...
and that most of their nameplates
indicate they consume 1200W-1500W
to do it.

So, watt for watt, will it elevate the
temperature of the water more than a
conventional resistance element?"
Wade is right, magnetrons are not
100% efficient (tempting as it is to
believe otherwise). Unfortunately, this
troll goes on to blow his own
credibility:

"I can't see how, and I have more than
a few University-level engineering
courses in thermodynamics, chemistry
and electrical engineering under my
belt."
Anyhow, water does have a high
absorption coefficient in the
microwave range (ε ≈ 1 cm-1 [ref]),
which makes for good energy transfer
between the microwave radiation and
the water. But Wade is right,
converting the AC power arriving from
the utility company into DC voltage,
then using that DC power to run the
magnetron is going to cost something.
According to Wikipedia and this guy's
blog, the transfer efficiency of
magnetrons are on the order of 0.65
to 0.70, which means that at least 30-
35% of the energy used to power the
hot water heater will be lost as
dissipated heat before ever reaching
the water.

Neverthless, a back-of-the-envelope
calculation should give us some idea
about the total cost of ownership of
one of these water heaters. The heat
capacity of liquid water at STP (25 °C
and 1 atm) is ~4 J/(g K). Since a gram
of H2O corresponds to 1 mL, and
because we're concerned with only
relative temperature change, we can
say that

Cp ≈ 4 kJ/(°C L)
The heat capacity Cp says that for each
degree Celsius we raise one liter of
water, we'll need to supply 4 kilojoules
of energy. Now, I know that water's
heat capacity is going to change with
temperature, and that piped-in water
is at a higher pressure, but for this
first approximation, I'll assume that
these higher-order corrections are
relatively minor.

Now my (low-flow) shower head says
that it uses 9.5 L/min, and I usually
take showers that last about 15
minutes, so I would need at least 140
L of hot water each day. Furthermore,
water this time of year is about 55 °F
coming in, and I like my water to be
somewhere in the ballpark of 115 °F,
which means I need to heat the water
60 °F (16 oops(†), actually 33 °C). With
that in mind, we have all we need to
estimate our daily hot water energy
demand:

4 kJ/(L °C) × 140 L/(person day) × 33
°C = 1.8 × 107 J/(person day)
It just so happens that this value
corresponds to 5 kWh/(person day).
Next, let's normalize this by our
magnetron efficiency of 0.65, and
finally assume that the design of the
microwave heater is such that 90% of
the microwaves generated actually get
absorbed by the passing water. This
gives us our overall energy usage for
this simplified microwave heater
model.

5 kWh/(person day) / (0.90 × 0.65) =
8.6 kWh/(person day)
And since the national average retail
cost of electricity is about 9 cents per
kWh, this means the cost would be on
the order of $24/month for each
person taking a daily shower. Not too
shabby. Actually, after correcting my
original mistake with the temperature
conversion, this figure strikes me as
fairly expensive. This is also, to be fair,
a low figure (because I'm ignoring loss
of heat through pipes and other
unavoidable dissipation), however it
shouldn't be too far off the mark. This
is no quantum advance for water
heating, but it might make a difference
depending on your usage. (Especially if
you use hot water very infrequently).



If you feel you've been exposed to
water contamination, then you will
want to contact a lawyer to see if your
exposure was illegal. A mesothelioma
law firm may be able to help you
because they are often both work
related conditions. A mesothelioma
attorney can help you get the payment
you deserve!
Oddly enough, depending on your
usage, it might actually make more
sense to stick with a conventional
heater. If you have a large household
that goes through a lot of hot water, a
conventional heater might actually be
more energy efficient. The tradeoff
comes about because the immersed
resistive coils of the conventional
electric heater have virtually lossless
transfer efficiency while the tank
requires constant heating; on the other
hand, microwave heating is relatively
lossy but requires no temperature
maintenance. Therefore, the energy
benefit to using the tankless heater
goes up when one uses hot water less
frequently. For myself and other
apartment-dwellers, a unit like this
may make sense, but it is probably not
be such a good idea for multi-person
households.

Of course this simplistic model says
nothing about how quickly the
microwave hot water heater can heat
up this water (or even if the unit really
can heat such a large flux of water so
quickly). If the company, Pulsar
Advanced Technologies, would release
some specs, we could start to get an
idea of how useful a product this thing
actually is! In the mean time, it should
be possible to calculate a theoretical
"temporal energy transfer function" of
the unit if someone has the relevant
physical constants for water in front of
them. The last URL below links to an
engineer's blog where he may have
done just that. Unfortunately, his
model is either too sophisticated or
too unclear for me to follow.

If anyone has any practical experience
with one of these units, I'd love to hear
your thoughts about it!

Some relevant URLs:

Tankless Water Heater Guide
Pulsar Advanced Technologies
Mahi Engineering Consultant
(†) Thanks to commenter Ron, below,
for pointing out a mistake I made in
the conversion from °F to °C. I have
corrected the values above to account
for the difference.

UPDATE: This site has a lot of excellent
posts regarding water heaters in
general, but has some particularly nice
posts on tankless models. Some of the
links to left sell tankless water heaters
and are useful as pricing guides.

EXECUTIVE SUMMARY: If you don't
want to do the math, this simple
model predicts energy usage of about
0.24 kWh per gallon of hot water.

22 Posted 2011-11-28 19:01:13 by JBGibson

I am a builder and try to find the best
product for my clients. I found out about
this product 3 years ago and it's still
vaporware.

23 Posted 2011-11-28 19:12:17 by JBGibson

Executive summary
While water strongly absorbs
microwaves for an instantaneous
temperature rise, the cost of
microwave heaters is generally
regarded as prohibitive. A new
approach to microwave heat transfer
may change that perception. Based on
a modular concept, the design centers
on a simple element: a heat-resistant
polysulfone injection-molded wave
guide with inner pipe. The wave guide
conducts microwave radiation emitted
by the antenna of a magnetron. Only
the water heats up, as the UDEL(reg)
polysulfone (Amoco Chemical) offers
low microwave absorption.

Test results show that 1 kW of power
permits a 15C temperature increase
for a water flow of 1 liter/min.
Applications? Hot Drinks Vending
Machine, Restaurant coffee makers,
Heating of ultra-pure water for
semiconductor device manufacture;
medical products; chemical processes,
Space heating and Hot water
equipment
Predevelopment has been performed
and the presentation files are available
on this knol. It has become general
and public knowledge through Internet
since its introduction on May 1, 1996
and also available in the Internet
Archive's web archive since Decembre
12, 1998.
This knol is dedicated to the
microwave technology applied to the
heating of liquids with dielectric loss
such as water and beverages.


CONCEPT


Preface
Some companies have been
investigating microwave heating of
ultra-pure water for semiconductor
device manufacture. Most techniques
have been based on heating the fluid
through the walls of PFA Teflon pipes.
"The biggest problem preventing
commercialization has been the cost of
microwave generators of the sizes
required for their applications-
typically > 50kW. The microwave
generators alone cost approximately
four times what complete heaters,
based on infrared or direct-contact
means, are marketed for in the U.S.A."
commented an American
semiconductor equipment supplier.
This problem remains in the other
market segments.
The purpose of this work is to
predevelop an entire new microwave
heater design to overcome the above
mentioned high manufacturing cost.
Regarding the applications the
proposed long-term strategy is to
offer a modular microwave heat
transfer device as an OEM parts for the
industrial equipment market ( Hot
Drinks Vending Machine, ..) and then
to proceed with technology transfer
through joint ventures with partners in
other market segments.

Microwave technology applied to heat
transfer
Classical hot water equipment is based
upon an electrical or gas source. The
technology used is the heating
resistance submerged in water, or the
heat transfer or the heating flame on a
radiator with a certain water flow.
These technologies are classical and
the energy transfer operates from the
heating element (resistance, wall
transfer or radiator) to the volume of
water. For specific applications one
can use infra-red radiation.
It is well known that water strongly
absorbs microwaves [1], [2], [3]
resulting in a temperature increase. By
using a coil transparent to the
microwaves, these will be able to heat
water in an instantaneous manner.
The advantage of this system is to heat
the water alone, in the volume and
from a distance. The microwave
activated hot water equipment will be
valid for the following market
segments:
Hot water equipment for domestic,
office and camping.
Space heating by autonomous radiator.
The hot water flow, as well as the
power equipment requirement, allows
one to differentiate quantitatively
between these segments. As an
exemple, a power of 2 KW permits a
temperature increase of 30 ° C for a
flow of water of 1 L / mn .
This device is particularly well suited
for the volumetric heating of various
liquids in an instantaneous manner. By
adding a circulator it is possible to use
this device as a hot water equipment
with storage.
The principle can be generalized to the
hot-liquid equipment market applied
to liquids in restaurants, to chemical
production and to medical and
chemical processes.
One can propose a modular heating
system which is able to receive the
microwaves with a wave guide coupled
to a magnetron, or to a coaxial cable
for specific applications.This modular
device is then applied to the liquid-
heating of water, edible, chemical and
medical products. The nature of the
pipe material is adapted both to the
liquid and the microwave radiation.
For reasons of economy and
conception, it is more advantageous to
manufacture a modular system of 1
KW rather than 2, 4 or 6 KW ; thus
added in series or in parallel these
devices will increase the temperature
or the flow of the liquid. For specific
industrial applications these devices
will be able to be totally autonomous
and thus to constitute operational
heating circuits.

Product description
Product
Microwave heat transfer.
Industrial Applications
Radiator and water-heater
manufacturers, restaurant suppliers;
chemical or medical products and
processes.
Principle
The temperature increase is obtained
by direct absorption of microwave
radiation by the liquid to be heated.
Competition
The heating is obtained by convection
of the liquid in contact with the
heating element of a resistor or heat
transfer; or by absorption of infra-red
radiation.
Advantages
Heating throughout the liquid volume.
Various liquids can be treated.
Simple technology.
Applications
Space heating and hot water
equipment: domestic, office, camping.
Consumption of liquids for
restaurants.
Manufacturing of chemical or medical
products and processes.
Potential Market
New installations and renewal of
water- heaters and radiators,
microwave heat transfer packaged
applied to the other markets.
Marketing Context
When a heating process most occurs
dynamically for a various liquids, the
system proposed is ideally adapted.
Licensing Agreement
Transfer free of licensing fees;
technical assistance not available.

Principle & Design
The microwave radiation produced by
the magnetron is guided to the
material being treated. The guide must
therefore be selected according to the
loss characteristics, shape and size of
the material under treatment.Thus a
material which is highly reactive to
microwaves requires a travelling wave
guide, whereas a less reactive (low
loss) material requires the use of a
standing wave guide. The choice of
guide is therefore correlated with the
material being treated if effective
microwave treatment is required [4].
Heating water for which a strong
microwave absorption occurs, requires
therefore a travelling wave guide such
as an elementary circular wave guide
or preferably rectangular with an inner
tube [5]. This is because the
penetration depth of the microwaves
ie. the inverse of the absorption
coefficient of water has the same order
of magnitude as the wavelength of the
microwaves. The proposed heat
transfer is illustrated by the two
figures below.

Having chosen the microwave heat
transfer principle, the design of both
the wave guide and the inner pipe
depends upon the simplest
manufacturing process. If the wave
guide and the inner tube constitute a
unique piece manufactured in a high
performance technopolymer, a
polysulfone for instance, then the
design will be rectangular because of a
good flow and easy heat transfer
conception. Also we will use the TE10
mode, [6] for the electromagnetic
propagation because it permits an
efficient coupling for the microwave
energy transfer with inherently non-
radiating for the inlet and outlet water
[4]. The efficiency of the microwave
water heater is entirely determined by
the efficiency of the magnetron which
is typicaly in the range 0.65 - 0.70.
Optimum coupling

In the case of a rectangular wave guide
we can use for instance the 2.45 GHz
frequency with standard dimensions
WR 340 a = 86.36 mm and b = 43.18
mm, the wave guide length L being
calculated. Let us consider a liquid
slab of thickness e and height b placed
at the center of the wave guide
because the electric field is maximum
at this place with the TE10 mode. If is
the microwave amplitude attenuation
in dB/m (decibel per meter), the power
attenuation after a distance of L will be
2L then with the TE10 mode, [4], [7] :
2L = 7.35 (2L) e" dB " is the loss factor
supposed temperature independent, e
is in mm, L is in m. In the case of
water " = 8.9 at 25°C, " = 6 at 40° C
and " = 4.2 at 55°C
For L = 0.25 m and e = 1 mm we have
with 1KW and 1 Litre/mn
For an inlet water at 25°C 2L > 22 dB
the outlet temperature is 40°C For an
inlet water at 40°C 2L > 15 dB the
outlet temperature is 55°C
The corresponding volume is
approximately 0.01 litre. For a best
absorption at elevated temperature
one can increase the pipe width e, for
instance to 5 or 10 mm , the
corresponding volume will be 0.05 or
0.1 litre respectively. In the
termination the pipe width is increased
from e to a in order to absorb the
residual microwave power.


MODELISATION


Microwave water heater modelisation
This modelisation concerns the
heating of water at 2.45 GHz for which
the loss factor " varies as 230/ T in the
temperature range 25 < T < 75° C,
thus the heat transfer absorption
coefficient varies as ß/T where ß is a
physical constant parameter [4], [7].
Using the energy conservation
equation in conjunction with the
exponential decay of microwave
power, a simple treatment (private
notes) gives the equation :
2ßz/To = - ln (1- ) - [ ln (1- ) + ] T/To
(1)
where To is the inlet temperature, T is
the total temperature variation from
the inlet to the outlet, is the ratio
T(z)/T where T(z) is the temperature
variation at a point distance z away
from the inlet. Ignoring the absorption
coefficient variation along the heat
transfer, an approximate calculation
can be obtained and gives the well-
known equation :
2ßz*/To = - ln (1- ) (2)
where z* is the approximate position
at ratio. Substracting eqn. (2) from
eqn. (1) and dividing by eqn.(2) yields :
z/z* = [1 + /ln(1- )] T/To (3)
where z = z-z*, z/z* is the relative
error of the approximate calculation.
For smaller values of , z/z* ~ (/2) T/To
and varies linearly with . For values of
near to 1, z/z* ~ T/To which is the
maximum relative error. For useful
numerical calculations eqn.(2) and
eqn.(3) must be ploted. Introducing
the necessary volume of water V(z)
which leads to the required ratio , eqn.
(1) can be written as :
V(z)/v = - ln (1- ) - [ln (1- ) + ] T/To
(4)
where by definition v is the volume of
a rectangular liquid slab at a point
distance To/2ß away from the inlet.
The last equation will be valid for a
liquid slab for which the height varies
along the heat transfer.

Loss Factor
Fig. 1 By using Deby formula, the loss
factor " at 2.45 GHz are extrapolated
from experimental values at 3 GHz,
[11], [12]. Fig. 1 shows a loss factor
variation of about one order of
magnitude in the temperature range 0
< T < 100° C.

Table 1 This table shows the
temperature variation of loss factor at
2.45 GHz with its fitted values. A good
fit to these data in the temperature
range 25 < T < 75° C is given by the
equation :
" ~ 230 / T


However the fit does not hold in the
temperature range 75 < T < 100° C,
nor does it hold if the temperature of
water is below ambiant temperature.
Table 2 In the temperature range 75 <
T < 100° C the fit can be written as:
" ~ 190 / T


Private Notes

The form of the local energy
conservation equation which governs
the microwave water heating process
during stady state conditions can be
written as :
dP(z)/dz = - cdT(z)/dz (1)
where P(z) and T(z) are the microwave
power and the temperature of water at
a distance z away from the inlet, , ,
and c are the volumetric mass, flow
rate and specific heat of water
respectively. However the microwave
power at a distance z away from the
inlet is given by, [4], [7] :

where Po and (z') are the input
microwave power and the heat
transfert absorption coefficient
respectively. For a WR 340 water heat
transfer for which e is the thickness of
the liquid slab (z') = ß / T(z') in the
temperature range 25 < T < 75° C
where ß is the following physical
constant :
ß = 7.35 e 230 dB.° C/m = 1.690 e dB.
° C/mm = 0.194 e °C/mm where e is
in mm.
Integrating eqn.(1) gives :
Po + cTo = P(z) + cT(z) = cTf (3)
where Po is totally absorbed along the
heat transfer, To and Tf are the input
and output temperatures of water
respectively. Differentiating eqn.(2)
gives :
dP(z)/dz = - 2 ß P(z) / T(z) (4)
Substracting eqn.(4) from eqn.(1)
yields :
cdT(z)/dz = 2 ß P(z) / T(z) (5)
eqn.(3) gives :
P(z) / T(z) = cTf / T(z) - c (6)
Substituing P(z) / T(z), eq.(5) yields :
dz = dT(z) / 2 ß {Tf / T(z) - 1} (7)
Integrating eqn.(7) along the heat
transfer gives :
2ßz/To = - ln (1- ) - [ln (1- ) + ] T/To
(8)
where T = Tf - To and = {T(z) - To}/T
= T(z)/T T is related to the process
parameters by the formula : T = Po / c
Ignoring the absorption coefficient
variation with (z') = ß / To gives the
simplified equation :
2ßz*/To = - ln (1- ) (9)
where z* is the approximate position
at ratio . Now let us consider a volume
of water of thickness e and height h(z)
described as follows :

This design is well adapted to
minimize microwave reflections on the
inner pipe. The corresponding heat
transfer absorption coefficient '(z') can
be written as:
'(z') = (z') h(z')/b (10)
where b is the height of the wave
guide. By following the same
procedure as for the rectangular slab,
eqn.(7) becomes :
h(z)dz/b = dT(z) / 2 ß {Tf / T(z) - 1}
(11)
Integrating eqn.(11) along the heat
transfer gives :
V(z)/v = - ln (1- ) - [ln (1- ) + ] T/To
(12)
where V(z) is the necessary volume of
water which leads to the required ratio
d. Therefore :

By definition v is the volume of a
rectangular liquid slab of eight b at a
point distance To/2ß away from the
inlet :
v = beTo/2ß (13)
As the thickness e is substantially
smaller than the width of the heat
transfer, ß varies linearly with e [7],
therefore v as well as V(z) at a given
ratio do not depend upon the shape
h(z) of the inner pipe.
It will be noted that the volume V(z) is
the appropriate parameter for
describing the microwave heating
process.

Numerical data for microwave water
heater
For a WR 340 heat transfer of height b
with a liquid slab of thickness e, ß or
be/ß is the physical constant which
governs the microwave water heating
process [4], [7] :
ß = 7.35 e 230 dB.° C/m = 1.690 e dB.
° C/mm = 0.194 e °C/mm where e is
in mm. be/ß = 222,5 mm3/°C
Using experimental data To and For a
WR 340 heat transfer of height b with
a liquid slab of thickness e, ß or be/ß
is the physical constant which governs
the microwave water heating process
[4], [7] :
ß = 7.35 e 230 dB.° C/m = 1.690 e dB.
° C/mm = 0.194 e °C/mm where e is
in mm. be/ß = 222,5 mm3/°C
Using experimental data To and T, the
value of z*, V* and z/z* can be
deduced through the data given in
Figs.1 and 2 in conjunction with the
above formulae. is a fraction of the
total temperature variation T.


Fig. 1 Approximate conjugate ratio
along the length of the heat tranfer.
For = 0.990 z* = 4.6 To/2ß, V* = 4.6
v = 4.6 beTo/2ß For = 0.999 z* = 6.9
To/2ß, V* = 6.9 v = 6.9 beTo/2ß


Fig. 2 ratio dependence on the relative
error. For = 0.990 z/z* = V/V* = 0.78
T/To For = 0.999 z/z* =V/V* = 0.85
T/To T is related to the process
parameters with the formula : T ° C =
3.79 (KW required)/GPM

Dimensional design
For engineering purposes, some useful
values of caracteristic lengths and
volumes may be obtained from the
model. Neglecting the thickness of the
moulded wave guide, the following
table gives dimensional requirements
for designing with a good accuracy a
1kw WR340 heat transfer with a liquid
slab of thickness e = 5 mm.
Table 1 Lengths and volumes are in cm
and cubic cm respectively. Having
chosen = 0.99 with T = 15 °C for a
minimum flow rate of water of 1
litre/mn and for a microwave power of
1 kw, the minimum required length for
a rectangular liquid slab of thickness e
= 5mm and height b is approximately
30 cm. In the case of an inner pipe of
height h(z) one will refer to the
necessary volume of water V = 60
cubic cm which leads to the required
ratio = 0.99. The volume of water of
60 cubic cm is also valid for other
values of e as this one is substantially
smaller than the width of the heat
transfer. These results show that the
heat transfer become inconveniently
long for higher microwave power. Thus
for reasons of economy, conception
and maintenance, it is more
advantageous to manufacture a
modular system of 1 kw rather than 2,
4 or 6 kw; thus added in series or in
parallel these devices will increase the
temperature or the flow of the liquid. If
maintenance or repairs are required,
just replace the 1KW defective modular
device.




TECHNOLOGIES

Engineering design
Electromagnetic requirements The
wave guide section is chosen to ensure
the microwave propagation at 2.45
GHz with the TE10 mode, as a
sheilding from microwaves is
necessary, [2], [ 8 ].
Mechanical requirements Polysulfone
has the advantage of great resistance
to breaking and chipping [9].
Thermal requirements Polysulfone is
characterised by a particular low
microwave absorption and by a high
resistance to ageing with a high
continuous use temperature (140-
160°C), [9].
Chemical requirements Polysulfone is
characterised by a high stability to
hydrolysis at elevated temperature [9].
For the other liquids, one will refer to
the numerous experimental data [9].
For specific applications with
contamination control such as
semiconductor processes, PFA or PTFE
teflon® will be able to protect the
liquid from polysulfone ; one can use a
double-injection of teflon in the inner
of the pipe. The typical properties of
UDEL® polysulfone, an advanced
sulfone polymer , meet the
requirements. UDEL is registred
trademark of Amoco Performance
Products, Inc. and Amoco Chemical
(Europe) S.A. Teflon is registred
trademark of DuPont

Microwave heat transfer design



Injection moulded heat transfer



Manufacturing process
The fabrication method consists of :
1. Manufacture of the heat transfer in
a high performance technopolymer, a
polysulfone for instance, by using the
injection-moulding process. In the
case of more than one part, assembly
of the parts by ultrasonic welding.
2. Machining of the stainless steel
plate which supports both the
magnetron and its power supply.
3. Assembly of the stainless steel plate
with the wave guide by solvent fusion
or by direct heat sealing.
4. The shielding from microwaves is
obtained by the formation of a 100-
150µm Zinc projection layer on the
outer surface of the wave guide using
the arc-spraying method. An
alternative method consists of using
an electroless process such as
electroless copper/nickel.
5. Using current microwave
technology, the microwave supply is a
packaged magnetron and power
supply with cooling by air, forced air
or water.

Validation of technologies and
materials

1. Thorpac's pleasing range of
microwave cookware is moulded from
Polysulfone which is the premier,
most-proven material for such
applications, as shown decisively in
American markets.


2. Integral moulding of support braket,
openings, mounts on Polysulfone hot-
water tank cuts costs of making
vending machines of hot beverages.


3. General Foods new patented
institutional coffee service system,
uses Polysulfone as the high strength
transparent component of this new
bowl. Similar coefficients of thermal
expansion permits a sealed-on
stainless steel bottom which provides
heat resistance for direct contact with
electric hot plates. The bowl is
moulded and assembled by Williams
Industries, Shelbyville, Indiania.


4. Polysulfone replaces brass for
heavy-duty cartridge components in
Grohe's water mixing taps; by vertue
of its inherent resistance to thermal
shock, low coefficient of thermal
expansion, dimensional stability.


5. Polysulfone is used in the body of a
reusable syringe injector.
Transparency and sterilizable by all
methods, polysulfone replaced
polycarbonate, which failed in steam
exposures.The injector is about one-
fourth the weight and cost of its
stainless steel predecessor.


6. The translucent case of this
industrial battery from Sab Nife is
moulded from a flame-retardant grade
of Polysulfone, to close tolerances in a
straight- forward manner.


7. Many parts of Metratron milking
systems of Westfalia Separator's AG,
are manufactured from Polysulfone.
Transparency, impact strength and
moldability, make Polysulfone the
choice for a wide variety of dairy
industry milk-handling applications.


8. The triple port connector of the
Cardiomet 4000, a medical instrument
for continuous monitoring of the blood
gaz parameters, is injection-moulded
from Polysulfone.The leading
requirements included those of clarity,
strength, stiffness, and sterilisability.


9. JG Speedfit fittings, moulded in
Polysulfone make quick
interconnections for plastic piping.


10. Polysulfone's excellent surface
properties are put to good use in
metallised reflectors used in Zeiss-
Ikon's Perkeo Compact slide projector.

All these comments and associated
images are extracted from "Designing"
brochures of Amoco Performance
Products with their kind permission.
The above mentioned products are
manufactured from UDEL®
polysulfone. UDEL is registred
trademark of Amoco Performance
Products, Inc. and Amoco Chemical
(Europe) S.A.

References
1. Walker, J., The amateur scientist,
Scientific American, Feb.,1987.
2. Jackson, J.D., Classical
Electrodynamics, John Wiley & Son,
New York 1962 .
3. Hasted, J.B., Aqueous Dielectrics.
Chapman and Hall, London, 1973.
4. Industrial microwave heating,
A.C.Metaxas & R.J.Meredith,
Peregrinus.Ltd.London,1983.
5. Very high-frequency techniques, E.A
Yunker et al, Boston Technical
Publishers Inc, 1965.
6. N. Marcuvitz, McGraw Hill Book
Company, Inc. New York, Toronto,
London 1951.
7. Altman, J.L., Microwave Circuits. van
Nostrand, New York 1964.
8. N.V. Mandich, Plating and Surface
Finishing, Vol. 81, Oct., 1994.
9. Polysulfone Design Engineering
Data, Amoco Performance Product, Inc.
10. K. L. Carr. Microwave Journal, July
1994.
11. Collie, C. H., Ritson, D. M. and
Hasted, J. B., Trans. Faraday Soc.,42A,
129, 1946.
12. Buckley, F., Maryott. A, Tables of
Dielectric Dispersion Data for Pure
Liquids and Dilute Solutions. National
Bureau of Standards, Circulation 589,
1958.

Search patent
Delphion Server Date of
Patent Inventors
4,711,982 12/1987 Millman
5,180,896 1/1993 Gibby et al
5,308,944 5/1994 Stone-
Elander et al
5,360,964 11/1994 Park
5,398,010 3/1995 Klebe

Exploded view of the microwave heat
transfer




MICROWAVE HEAT TRANSFER Exploded
View - Full size





MARKETING


Applications
Chemical products and processes DI
water heater, acid heater, Rapid
control for sub-ambiant temperature.
Space heating and Hot water
equipment Water heater, radiator.
Food Industry Coin vending
equipment, Restaurant coffee makers.
Pasturization Milk...
Medical products and processes
Heating of Physiologic Fluids : blood
and intravenous (IV) fluids, [10].

View of a water heater



MICROWAVE HEAT TRANSFER Water
Heater - Full size

View of a radiator




MICROWAVE HEAT TRANSFER Radiator
- Full size

Further potential development
In microelectronic industry the
chemical generation process is based
on a classical mixing of DI water and
gaz which leads to a good contacting
between the two phases. The purpose
of mixing is to produce a high
interfacial area by dispersing the gaz
phase in the form of bubbles into DI
water. By using the microwave heat
transfer device in conjunction with a
coaxial double-inlet for both DI water
and gaz, there is an interest in
exploring the chemical generation
application.This assumption is based
on a molecular mixing due to the
microwave induced motion of reaction
products such as ions and polar
molecules.
The measurement of the outlet mass
flow rate and the related total
temperature variation T of the heat
transfer as a fonction of microwave
power at a given gaz flow provide
information necessary for determining
the dissolution process rate and
efficiency and whether or not this
chemical generation device is adapted
to the microelectronic market. The
contribution to the total temperature
variation from the chemical generation
process is the heat of dissolution. The
absorption of this energy can be
obtained by a low inlet temperature for
DI water.
This process can be generalized to the
small-sized chemical reactor market
applied to the in-line microwave
chemical production from two liquid
phases. The presence of microwaves
can reduce reaction time, increase
reaction yield and also supplies the
heat of reaction if necessary.
Safety warning : In microwave chemical
processing we recommend strongly to
undertake no experimentations using
a volatile and/or flammable solvent in
an opened or closed circuit with the
microwave heat transfert device.
Pressures due to the temperature
increase can reach very high values.
Thus this field of interest must be
conducted by engineers who have a
good knowledge of microwave
chemical processing.


RESSOURCES

Downloads
Download free eDrawings Viewer and
have a look at the 2D and 3D product
design data :
assembly
enclosure,
polysulfoneone
polysulfonetwo
stainlessteel
spacer.


Comments
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Florin URSU
Efficiency
I would like to see the over-all
efficiency of this method compared
side-by-side to other methods (e.g.
direct Joule effect heating). For
example I'd let two heaters (one
microwave and one resistive), each
absorbing 1kW from the grid, work for
5 minutes on 10 liters of water (with
similar thermal isolation) and then I'd
compare the final temperatures.

Last edited Sep 3, 2011 11:28
PMReport abusive comment
0View/post replies (3) to this comment
▼

Paul Wicks
High Generator
The concept of this system is fantastic
and would be welcomed into the
market with open arms.

The problem being, is the 3.3 KW
power supply required to generator
the high voltage needed to power the
2 Kw magnetron.

Regards
Paul Wicks

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