Grantee Research Project Results
Final Report: Babington Net-Power, Multi-liquid Fuel Heater/Cooker
EPA Contract Number: EPD17003Title: Babington Net-Power, Multi-liquid Fuel Heater/Cooker
Investigators: Hamer, Andrew
Small Business: Babington Technology, Inc.
EPA Contact: Richards, April
Phase: I
Project Period: November 1, 2016 through April 30, 2017
Project Amount: $99,485
RFA: Small Business Innovation Research (SBIR) - Phase I (2016) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR)
Description:
This report summarizes results of the Phase 1 efforts by Babington Technology Inc., in SBIR EP-D-17-003 from the US EPA, to investigate methods of providing cooking, heating, and net electrical power in a combined appliance. The Babington proposal centered on the use of the Babington atomization principle in liquid-fuel combustion to develop an alternative to biomass fuels and to exploit the excellence of combustion already achieved in practical burners. The Babington atomization method is unique; it turns the nozzle “inside out”, precludes fuel-orifice clogging, and produces fine particles. The liquid fuel particles are so fine that they can contain 1,000 times less fuel than droplets produced by conventional pressure nozzles depending on the configuration and heating requirement. When liquid fuel is atomized to this extent and together with good mixing, it will ignite instantaneously, and burn cleanly, and smoke-free. The overarching challenge is how to provide net power while powering the liquid-fuel burner, and yet make the combined appliance affordable. Secondary challenges involved integrating the major components to advance a controllable, easy to use, safe, and reliable system. Our Phase 1 efforts tackled these issues.
Summary/Accomplishments (Outputs/Outcomes):
Because of the multi-liquid fuel burner’s combined low power consumption and variable firing rate capability with its multi-functional use, the platform supports Institutional scenarios in environments where electricity is unreliable, scarce or unavailable. In the course of integrating the major components, we focused on a practical design and gained confidence in the validity/feasibility of the approach as being worthy of further pursuit and investment. The major achievements were:
• Demonstrating a basis for such an appliance to be used as an Institutional Cookstove, and
• Confirming application definitions, and evolving Technical Guidelines for going forward with two approaches (integrated power generator vs. external power, including renewable energy sources).
Demonstration of All Three Functions in a Physically Integrated System
We combined the FlexFire™ burner with a 200-watt lead-telluride thermoelectric converter as our power technology, and an adapted Babington stockpot heater. Once integrated, the system became a valuable learning tool. The integration effort uncovered the affects the burner has on the thermoelectric converter (TEC) and the affects the TEC has on the burner. In summary, we were able to prove that the system will reliably produce net power, achieve high efficiency, while generating clean emissions.
Power
After several trials with various mantle designs, we produced 185 watts, while consuming only 68 watts (burner plus pump), and thereby demonstrating that the system will generate net power. Based on the trials, we are confident we can produce more power by increasing the firing rate of the burner, but we may need to improve the heat distribution on the TEC hot frame. The method normally used to achieve and verify uniform heat flux is to use a well-instrumented simulated hot frame.
Phase 1 to Field Trials
We also investigated methods of providing power other than physically integrating a power generator into the appliance. Cooking in institutional settings involves multiple meal cycles typically lasting only for a few or several hours per meal cycle, depending on the type of foods being prepared. We conclude that it is feasible to use small solar panels (or other renewable energy sources) with a storage battery, to power the burner when needed, even when sunlight is not available.
Emissions
The Babington atomization principle achieves excellent combustion because of the ultrafine droplet size and well-designed mixing of the fuel droplets with air. Our concern was that the tight coupling of the components in their integration would adversely affect combustion by either: distorting mixing, impeding the air flow, or simply over-quenching the flame as it impinges on the heat distribution mantle. In particular, a shortage of air flow or flame quenching can produce copious quantities of carbon monoxide and/or soot. None of these turned out to be the case, and by being able to adjust the burner blower independently of the other functions, we maintained excellent combustion stability, as verified by the measured emissions. A sample of the emissions taken at steady state conditions is shown in Table 1. The smoke number on the Bacharach scale (0 to 9) was measured as zero, with zero being no detectable particulates in the exhaust. Not only was the exhaust gas clean, there was also no soot buildup, nor any trace of soot in any of the exhaust passages.
Efficiency
We were expecting high efficiency because of the clean performance of the FlexFire™ burner that is able to operate with little excess air. Indeed, that proved to be true. On a test 1 ppm = parts per million. run of over two hours on April 21st, we obtained steady-state fuel consumption data at a high, but not the highest, firing rate. The fuel weight data were regressed and average fuel consumption (2.6834 lb/hr) used to obtain the gross firing rate of ~50, 000 BTU/hr (~14.5 kW).
System efficiency can be considered from several points of view. If cooking is the priority, then all energies directed to functions other than cooking could be considered losses or inefficiencies. The heat lost in the exhaust stream, at the firing rate shown in Table 2 and exit temperature of 916°F, was calculated to be 12,161 BTU/hr (3.56 kW). The heat delivered to the TEC is estimated at 9,554 BTU/hr (2.8 kW). If electric power and the rejected heat from the generator are regarded as valuable outputs rather than losses, then the estimated cooking efficiency is increased accordingly, because the net heat available for cooking would be the basis for cooking efficiency calculation, rather than the gross firing rate. In either case, the efficiency is high.
Conclusions:
Integration task
Having previously decided on the power generator, burner, and stockpot heater, we began building a system around those chosen components to demonstrate a proof-of-principle version of a combined cooking, heating, and power generating appliance. For our proof-of-principle version, we had chosen the FlexFire™ Burner, the 200 W TEC, and a modified Babington Stockpot heater. We successfully heated the TEC to get 185 watts of output with excellent margins in cold side temperature, and could easily have obtained more power simply by increasing the firing rate.
TEC Power Output
When we ran the burner and TEC, we intended to load the TEC at its matched-load point and measure the power output. We designed a load whose resistance equals the design match point for the TEC and assembled the load resistors on large heat sinks. In the product, the TEC output would be directed to a 12-volt storage battery through either a Schottky diode or control-system driven relay. The power consuming components would be driven from the battery; the customer power would also come from the battery.
Stockpot Heater
The stockpot heater used for the integration test was a Babington design for a military kitchen, and was used for expediency in cost and schedule. Preliminary measurements of the exhaust gas temperature exiting the stockpot heater were in the 900°F range. That particular design of stockpot heater is very well insulated and the exterior surface temperatures are safe. This military kitchen heater design could be simplified and made much cheaper for commercial applications.
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