Method and apparatus for fluid temperature control

An apparatus and method for cooling or heating fluids, such as fuel in a fuel system of an automotive vehicle. Compressed gas is delivered to a vortex tube or air amplifier 14 so that the gas rapidly expands and cools, thereby cooling a first end 16 of the vortex tube 14 in relation to a warmer second end thereof 18. A first fuel inlet port 20 of a first heat exchanger 16 lies proximate the first end 16 so that fuel flowing into the inlet port 20 is cooled by thermal contact with the first end 16 of the vortex tube 14. A cooled fuel outlet port 22 in the heat exchanger 16 lies proximate the first end 16 so that cooled fuel may leave the heat exchanger 16 for delivery to an engine. A valve with an upstream gate 26 and two downstream gates 28,30 is located so that fuel is selectively delivered to the first fuel inlet port 20 through the upstream gate 26 and one of the two downstream gates 28,30 if cooling of the fuel is desired. The second downstream gate 30 is connected to a second fuel inlet port 34 in a second heat exchanger 18 so that fuel flowing therethrough is warmed thereby if heating of the fuel is desired. A warmed fuel outlet port 36 is provided in the second heat exchanger so that warmed fuel may leave the second heat exchanger 18. A temperature sensor 40 and valve controller are in communication with the valve.

TECHNICAL FIELD 
This invention relates to a method and apparatus for cooling and heating 
fluids, such as fuel for an engine. 
BACKGROUND ART 
In an internal combustion engine, engine performance is influenced 
significantly by the temperature of the fuel used thereby. Elevated 
temperatures decrease fuel density, which makes combustion less efficient. 
Additionally, fuel mass droplet size decrease with fuel density, as does 
flow rate, which results in less spray penetration. 
Today's diesel engines, especially those used in class 6, 7, and 8 trucks, 
have a very high injection pressure. This high pressure causes the fuel to 
become heated to undesirable temperatures. An injector pump pressurizes 
fuel to the injectors. The injectors only use 10-15% of the fuel that is 
provided to the injectors. The remaining 85-90% of the fuel is returned to 
the tank at a lower pressure, but still at an elevated temperature. This 
is not an insurmountable problem until the tank temperature or the fuel 
temperature increase beyond approximately 150.degree. F. At or beyond this 
point, various problems occur within the fuel. Also, its combustion 
efficiency may decline. This is a major truck industry concern which has 
not yet been solved satisfactorily through conventional cooling methods. 
The primary problem with fuel cooling is that one cannot mount an 
air-to-fuel cooler in the front of the vehicle or in the main cooling air 
stream due to the possibility of leaks or front-end collisions which may 
cause leaks to occur. This would be a simple and inexpensive means to cool 
the fuel, but is not practical or safe. 
It is undesirable to use conventional outlet water from the engine cooling 
system because the temperature of the radiator typically exceeds 
150.degree. F., even at the outlet. For heat transfer to occur, there must 
be a significant temperature differential between the fuel being returned 
to the tank and the water being used to cool it. 
Another conventional cooling alternative would be to use the air 
conditioning system. This too has some drawbacks because all trucks do not 
come equipped with air conditioning. 
During winter conditions it may become necessary to warm the fuel, 
especially during engine start up. In cold environments, diesel fuels 
become jelled and may cause fuel systems to freeze up. Conventional 
cooling methods described above do not provide for heating fuel when 
necessary. 
Representative of prior art approaches to the above-noted problems are 
found in the disclosures of U.S. Pat. Nos. 4,036,182; 4,924,838; 
4,898,141; 5,368,003; 5,251,603; and 2,994,331. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a fuel temperature control 
system. More specifically, the invention combines two technologies in a 
manner that provides a solution to any conventional cooling system. The 
invention also provides a means to provide both cooling and heating 
through utilization of one power source, i.e., compressed air. 
The invention is a method and apparatus for cooling or heating fluids, such 
as fuel in the fuel system of an automotive vehicle. 
The method comprises the following steps: (a) connecting a supply of 
compressed gas to a vortex tube or air amplifier so that the gas rapidly 
expands and cools, thereby cooling a first end of the vortex tube in 
relation to a warmer second end; (b) providing a first fuel inlet port in 
a first heat exchanger proximate the first end of the vortex tube so that 
fuel flowing into the fuel inlet port is cooled by thermal contact with 
the first end of the vortex tube; (c) providing a cooled fuel outlet port 
at the first end so that cooled fuel may leave the first heat exchanger; 
(d) locating a valve having an upstream gate and two downstream gates so 
that fuel is selectively delivered to the first fuel inlet port through 
the upstream gate and one of the two downstream gates if cooling of the 
fuel is desired; (e) providing a passage from the second downstream gate 
to a second fuel inlet port in a second heat exchanger at the second end 
of the vortex tube so that fuel selectively flowing therethrough is warmed 
by the second end of the vortex tube; and (f) providing a warmed fuel 
outlet port at the second end so that warmed fuel may leave the second 
heat exchanger for delivery to an engine. 
To implement the above method, the following apparatus is provided: (a) a 
supply of compressed gas connected to the vortex tube; (b) a first fuel 
inlet port in a first heat exchanger proximate a first end of the vortex 
tube connected so that fuel flowing into the fuel inlet port is cooled by 
thermal contact with the first end; (c) an outlet port for cooled fuel so 
that cooled fuel may leave the first heat exchanger; (d) a valve for 
selectively delivering fuel to the first end for cooling or to the second 
heat exchanger for heating the fuel; and (e) an outlet port for warmed 
fuel thereby allowing warmed fuel to leave the second heat exchanger for 
delivery to an engine. 
Additional objects and advantages of the present invention will be apparent 
from the following description considered in connection with the 
accompanying drawings.

BEST MODE FOR CARRYING OUT THE INVENTION 
With the above-mentioned drawbacks of conventional methods of cooling, a 
need for some other means of fluid temperature control has arisen. 
According to the method of the present invention, fuel in the fuel system 
of a vehicle can be cooled by connecting a supply of compressed gas 10 
(FIG. 1) to a gas inlet port 12 of a vortex tube or air amplifier 14 so 
that the gas rapidly expands and cools within the tube. A first end 
becomes cool in relation to a warmer second end as the compressed air 
rapidly expands. Connected to the first end is a first heat exchanger 16. 
A second heat exchanger 18 is connected to the second end of the vortex 
tube. 
A first fluid or fuel inlet port 20 (FIGS. 1-2) is provided in the first 
heat exchanger 16 so that fuel flowing in to the fuel inlet port 20 is 
cooled by thermal contact through heat exchanging media with the first end 
of the vortex tube 14. An outlet port 22 for cooled fuel is provided so 
that cooled fuel may leave the first heat exchanger 16 for delivery to an 
engine. 
The method of the present invention also contemplates heating fuel when 
desired. To heat or simultaneously cool and heat, a valve means 24, such 
as a conventional three-way valve, is provided with an upstream gate 26 
and two downstream gates 28, 30 so that fluid or fuel is selectively 
delivered to the first fuel inlet port 20 to cool the fuel through the 
upstream gate 26 and one of the two downstream gates 28. 
Connecting the second downstream gate 30 to a second fluid or fuel inlet 
port 34 in the second heat exchanger is a passage, or conduit 32. Fluid or 
fuel selectively flowing therethrough is warmed by the second end of the 
vortex tube 14. An outlet port 36 for warmed fuel is provided so that 
warmed fuel may leave the second heat exchanger 14 for delivery to a 
system operable therewith, such as an engine. 
In one embodiment of the apparatus, control means 38, such as 
microcontroller, microcomputer or microprocessor, is connected to the 
valve 24 for directing fluid or fuel flow through one or both of the 
downstream gates 28, 30 of the valve 24 to effect cooling or heating in 
response to a signal generated by a fuel temperature sensor 40. In this 
embodiment, the control means 38 may include a processor with control 
logic to open one or both of the two downstream gates 28, 30 based on the 
signal from the fuel temperature sensor 40. It will readily be appreciated 
that such control logic can be implemented by software, hardware, or a 
combination thereof. 
Turning now to FIGS. 2 and 5-6, in one embodiment of the invention, the 
first heat exchanger 16 connected to the vortex tube 14 comprises a heat 
exchanging tube 42 within which fuel to be cooled may pass through an 
annular internal passage 44. To promote efficiency of heat exchange, a 
turbulator (heat exchanger louvered fins) 46 is disposed within the heat 
exchanging tube 42. 
An alternate embodiment of the present invention is depicted in FIGS. 3-4. 
In that embodiment; fluid or fuel to be cooled passes along an annular 
passage 44 supported between radially mounted fins 48 within a central 
bore of the heat exchanging tube 42. Annularly mounted fins 56 are 
provided in an annular space between an inner tube 58 and the heat 
exchanging tube 42. 
The above discussion of the alternate embodiments indicate that the device 
can be configured in many ways to provide the desired air flow and outlet 
temperatures. 
In FIGS. 3-4, the external air or gas-deflecting fins 56 are bonded to the 
external wall of the tube 58. These fins are covered with another tube 42 
which serves several purposes. One is to hold the external air fins in 
contact with the external tube wall during the bonding process. A second 
purpose is to direct the air from the vortex tube 14 through the external 
air fins 56. This external tube can also be formed (FIGS. 7-8) in such a 
manner as to provide a plenum or connection volume between a heat 
exchanger or radiator 50 and the first (cooled) end 16 of the vortex tube 
14. 
This invention solves the need for an integrated fuel cooling/heating unit 
for fluid temperature control and does not add heat load to existing 
cooling systems. It is a system which can be effectively field installed 
in existing vehicles as well as in new O.E.M. vehicles. 
Another advantage is that the invention can be mounted in a safe area that 
will remain undamaged during a collision, such as inside the frame rails. 
It does not require ambient air, such as at the front end of a vehicle to 
provide cold air to the heat exchanger. This type of device can be used in 
any application requiring fuel temperature control as long as a source of 
compressed air is available. All class 6, 7 and 8 trucks use air 
compression systems for their air brakes. That air compressor may also 
provide sufficient air pressure for the disclosed fuel temperature control 
system to work effectively. Optionally, a dedicated air compressor system 
may be employed where the existing system does not have adequate capacity. 
As noted earlier, the invention can be used as a fuel heater. Several 
manufacturers currently build fuel heaters, but none produce a unit for 
both cooling and heating. 
Furthermore, an additional heat exchanger could be placed on the warm end 
18, or the air flow from that end could be baffled or routed into the 
existing cooler. Through the disclosed combination, both the fuel cooler 
and fuel heater can be in one combined unit. Multiple configurations can 
be envisioned to plumb either the air flows and/or the liquid flows to 
effectively heat or cool. 
As depicted in FIG. 1, the cold gas is furnished by a vortex device 14. The 
vortex device conventionally includes a vortex tube having an inlet 12 
which receives compressed air, typically at about 70.degree. F. Incoming 
air is delivered to a vortex-generation chamber (not shown) from which 
cold air emerges via end 16 in a cooled stream, typically at about 
-50.degree. F. Warm air exhausts from the warm outlet 18, typically at 
about 200.degree. F. Sources of vortex tubes include ITW Vortec, 
Cincinnati, Ohio and ARTX, Fairfield, Ohio. Other suitable devices are 
available from EXAIR Corporation, also Cincinnati, Ohio. 
Such designs operate on the vortex principle of fluid rotating about an 
axis. The vortex tube creates a vortex from compressed air and separates 
it into two streams--one hot and one cold. In operation, compressed air or 
an inert gas enters a cylindrical generator where it causes the air to 
rotate. Rotating air is forced down the inner walls of hot tube at speeds 
reaching 1,000,000 rpm. 
At the end of the hot tube 18, a small portion of this air exits through a 
needle valve (not shown) as hot air exhaust. The remaining air is forced 
back to the center of the incoming air stream at a slower speed. The heat 
from the slower moving air is transferred to the faster moving incoming 
air. The super-cooled air flows through the center of the generator and 
exits through the cold air exhaust port at end 16. The tube operates on 
filtered compressed air at about 100 psig. Preferably, gas is supplied to 
the vortex tube 14 at a pressure of approximately 10-120 psig. Typically 
used gases include air, nitrogen, argon, and carbon dioxide. 
In an alternative embodiment of the disclosed apparatus for fluid 
temperature control, an air amplifier may be connected to a heat exchanger 
instead of the vortex tube if cooling is desired. One suitable air 
amplifier is available from ARTX, Ltd. in Fairfield, Ohio. Such devices 
release a small amount of compressed air at near-sonic velocity through an 
adjustable, internal, ring-shaped nozzle. The high-speed "tubes" of air 
released through the front of the apparatus leave behind a strong vacuum, 
pulling additional surrounding air through the rear of the amplifier, 
while pushing the ambient air in front. 
In FIGS. 7 and 8, the vortex tube 14 is connected to a heat exchanger or 
radiator 50 via a plenum 64. In FIG. 7, fluid to be cooled enters the heat 
exchanger or radiator 50 at inlet 60 and leaves at outlet 62. The radiator 
of that configuration has a core which provides down flow and side flow of 
the fluid to be cooled. FIG. 8 depicts a plate-type heat exchanger 
configuration in which incoming and exiting fluid flows are parallel. 
While the best mode for carrying out the invention has been described in 
detail, those familiar with the art to which this invention relates will 
recognize various alternative designs and embodiments for practicing the 
invention as defined by the following claims.