The Cracker Test Facility

The cracker test rig provides both visual (observer) facilities, and PC based data-logging facilities.

Although all practical data is recorded, including ambient temperature, run time, time of day, date, etc., at every step, to enable the integrity of the system to be examined from all perspectives, the actual 'proof of functionality' is based solely upon the rise in temperature of the fixed volume load (circa 1.2 UK gallons of water) against the weight of fuel consumed.

The rig consists of an electric start 240 Volt + 12 Volt, 6.9 KVA, four-stroke OHV generator, driving into a conventional insulated hot-water tank, vented to atmosphere, equipped with a 2 kilowatt element.

Water level is determined by a fixed electrical continuity probe, located within the tank, monitored by the PC, with a narrow calibrated sight-glass, mounted at the side and top of the tank, for visual corroboration. The exhausted water is also weighed.

Fully isolated, battery operated devices are employed for displaying the fuel weights and water temperature and weight, in order to obviate all possibility of 'interference'. In all cases, the readings are manually entered into the PC on demand, by the observer.

Starting and stopping of the engine is carried out manually under the direction of the PC.

For each test, the engine is run 'off-load' for a 2-minute period, in order to flush the cracker chamber and carburettor of modified fuel prior to 'cracker off' runs, and to allow the cracker to fill the fuel system prior to 'cracker on' runs. The recorded fuel weight and water temperature readings are taken after the flushing period, prior to the monitored test run.

The AC circuit breaker is set to the 'on' position manually, under the direction of the PC, which has to detect a ten-second uninterrupted current flow before energising the heater element (via a relay) and beginning the recorded timing cycle. The heater has a hard-wired neon indicator.

At 'time-out' the PC switches the heater element off.

The PC controls the filling of the tank, via a conventional solenoid valve. The 'tank full' detector halts the filling cycle.

The tank is emptied manually, via a tap, with the water being drained into a bucket and weighed.

In order to keep the starting water temperatures similar, for every run, the tank is filled, drained and then refilled prior to each monitored cycle.

The water temperatures are monitored by a 4 digit display electronic thermometer, and the fuel weight is monitored by a high-resolution 6 digit display 'laboratory' type electronic weighing device. In all cases, the operator or observer, is prompted to enter the values into the PC at the appropriate times.

The cracker unit is electrically isolated during the 'cracker-off' runs, and entirely powered by the generator's 12 volt supply during 'on' runs, thus removing the need to include the cracker unit's electrical power demands in any calculations.

Cracker 'off' and cracker 'on' runs are carried out back to back, with the fuel tank being topped up to a similar starting weight between runs.

For practical reasons, cracker on, and cracker off, runs intended for efficacy calculations, will be of the same time duration, although the run times may be varied to suit third party requirements. For safety reasons, the water temperature will be limited to a maximum of 80 degrees centigrade, unless a rational objection to this limit is submitted.

The test procedure has been designed to reduce human interaction with the rig to a practical minimum, and allow all data to be entered into the PC to be verified and the entry carried out by the observer.

It will ultimately be shown that the above-described test-rig represents (as it should) a 'worst case' scenario, in that such a low fuel pressure arrangement does not well suit an operational cracker.

The PC program is written in PC DOS assembly language, recorded on and run from, a floppy disc. A text file annotated listing of the program is also contained on the disk, as will be a copy of the test data. At the close of session, this disc will be handed to any observer who requests it. No objections will be raised should any observer wish to test the integrity of the system. Note. This does not include the cracker's internal microprocessor program.

A copy of every such file produced for a third party observer, will also be recorded on the PC's internal storage device, and more than one diskette copy will be made available if required.

THE CIRCUIT

Only the water-heating element is powered by the generator's 230 Volt output, and only the Cracker unit is powered by the 12 Volt output. The heating element is permanently wired, with a directly connected and visible neon indicator, and is switched by the PC. The Cracker unit has a separate on/off switch with a 'power on' indicator, and is NOT controlled by the PC.

The PC, the electronic control circuits and the solenoid water valve are supplied via mains driven power supply units.

As it would be in a motor vehicle, the microprocessor controlled Cracker unit is an entirely independent and isolated device, powered only by the generator's 12 Volt output.

THE SEQUENCE

The PC and external control circuits are powered up, and may remain so throughout all of the procedures. At each step of the test sequence, the PC logs the time, as per it's internal clock, and also displays it on the screen.

1. With the circuit breaker in the 'off' position, the engine is manually started.

2. The PC detects that the engine is running, but waits for the operator to order the sequence to continue. (Initially, this provides for an engine warm up period.)

3. When in receipt of the 'continue' (carriage return) order, the PC times out a two-minute 'fuel flush' period.

4. The PC then operates the 'tank-fill' solenoid, and waits for the water level sensor to indicate 'full'.

5. The PC then times out a two-minute settle period.

6. The PC then directs the observer to drain the tank.

7. The PC then operates the 'tank-fill' solenoid again, and waits for the water level sensor to indicate 'full'.

8. The observer is then directed to examine the water-level sight tube.

9. The observer is then directed to ensure that the Cracker unit switch is in the 'off' position for first runs, or the 'on' position for second runs, and then hit 'continue'.

10. The observer is directed to read the water temperature, and enter it into the PC, and then hit 'continue'.

11. The observer is directed to read the fuel weight, and enter it into the PC, and then hit 'continue'.

12. The observer is then directed to set the circuit breaker to 'on', and then hit 'continue'.

13. The PC then switches the element on, and starts timing the pre-set run period.

14. At 'time-out', the PC switches the element off, and then directs the operator to kill the engine.

15. The PC then detects this, and times out a 2 minute 'settle' period.

16. The operator is directed to read the water temperature, and enter it into the PC.

17. The operator is directed to read the fuel weight, and enter it into the PC.

18. The operator is then directed to discharge the heated water into the bucket and to weigh it, and then enter the weight into to PC.

19. The PC then displays the test results that have been recorded, and waits for the order to re-run the entire sequence, with the cracker active.

Having carried out both runs, the results of the two tests, along with a comparative analyses, will be displayed in the same form as is ultimately used to produce a printed report, which is also generated on the diskette in TXT format.

NOTES.

The PC program runs in DOS and has been written in a particular 'linear' form (no significant sub-routines) such that any person with even only a moderate understanding of assembly code should be able to trace (Debug) and verify the integrity of operations. Also to this end, the exact same routine is called for both runs, the only difference being the energised or not energised state of the cracker unit, immediately prior to the run, which (as stated) is entirely powered by or isolated from the generator's 12 Volt output, and switched on and off by the observer. A fully annotated plain Debug text file listing is also included on the disk.