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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Final Technical Report: Thermoelectric-Enhanced Cookstove Add-on (TECA) for Clean Biomass Cookstoves

This program seeks to demonstrate a solution to enhance existing biomass cookstove performance through the use of RTI’s Thermoelectric Enhanced Cookstove Add-on (TECA) device. The self-powered TECA device captures a portion of heat from the stove and converts it to electricity through a thermoelectric (TE) device to power a blower. Colorado State University and Envirofit International are partners to support the air injection design and commercialization to enhance combustion in the stove and reduce emissions. Relevance: By demonstrating a proof of concept of the approach with the Envirofit M-5000 stove and TECA device, we hope to apply this technology to existing stoves that are already in use and reduce emissions for stoves that have already found user acceptance to provide a true health benefit. Challenges: The technical challenges include achieving Tier 4 emissions from a biomass stove and for such a stove to operate reliably in the harsh field environment. Additional challenges include the fact that it is difficult to develop a cost effective solution and insure adoption and proper use in the field. Outcomes: In this program we have demonstrated PM emissions at 82 mg/MJd, a 70% reduction as compared to baseline stove operation. We have also developed a stove optimization approach that reduces the number of costly experiments. We have evaluated component-level reliability and will be testing the stove prototype in the field for performance and reliability.

09 BIOMASS FUELS↗
DOE OSTI2013

Final Report: Wireless Instrument for Automated Measurement of Clean Cookstove Usage and Black Carbon Emissions

Black carbon (BC) emissions from traditional cooking fires and other sources are significant anthropogenic drivers of radiative forcing. Clean cookstoves present a more energy-efficient and cleaner-burning vehicle for cooking than traditional wood-burning stoves, yet many existing cookstoves reduce emissions by only modest amounts. Further research into cookstove use, fuel types, and verification of emissions is needed as adoption rates for such stoves remain low. Accelerated innovation requires techniques for measuring and verifying such cookstove performance. The overarching goal of the proposed program was to develop a low-cost, wireless instrument to provide a high-resolution profile of the cookstove BC emissions and usage in the field. We proposed transferring the complexity of analysis away from the sampling hardware at the measurement site and to software at a centrally located server to easily analyze data from thousands of sampling instruments. We were able to build a low-cost field-based instrument that produces repeatable, low-cost estimates of cookstove usage, fuel estimates, and emission values with low variability. Emission values from our instrument were consistent with published ranges of emissions for similar stove and fuel types.

09 BIOMASS FUELS↗
DOE OSTI2017

Verifying mixing in dilution tunnels How to ensure cookstove emissions samples are unbiased

A well-mixed diluted sample is essential for unbiased measurement of cookstove emissions. Most cookstove testing labs employ a dilution tunnel, also referred to as a “duct,” to mix clean dilution air with cookstove emissions before sampling. It is important that the emissions be well-mixed and unbiased at the sampling port so that instruments can take representative samples of the emission plume. Some groups have employed mixing baffles to ensure the gaseous and aerosol emissions from cookstoves are well-mixed before reaching the sampling location [2, 4]. The goal of these baffles is to to dilute and mix the emissions stream with the room air entering the fume hood by creating a local zone of high turbulence. However, potential drawbacks of mixing baffles include increased flow resistance (larger blowers needed for the same exhaust flow), nuisance cleaning of baffles as soot collects, and, importantly, the potential for loss of PM2.5 particles on the baffles themselves, thus biasing results. A cookstove emission monitoring system with baffles will collect particles faster than the duct’s walls alone. This is mostly driven by the available surface area for deposition by processes of Brownian diffusion (through the boundary layer) and turbophoresis (i.e. impaction). The greater the surface area available for diffusive and advection-driven deposition to occur, the greater the particle loss will be at the sampling port. As a layer of larger particle “fuzz” builds on the mixing baffles, even greater PM2.5 loss could occur. The micro structure of the deposited aerosol will lead to increased rates of particle loss by interception and a tendency for smaller particles to deposit due to impaction on small features of the micro structure. If the flow stream could be well-mixed without the need for baffles, these drawbacks could be avoided and the cookstove emissions sampling system would be more robust.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2019

Predicting and analyzing the performance of biomass-burning natural draft rocket cookstoves using computational fluid dynamics

Nearly three billion people in the world today rely on biomass for their cooking needs. Indoor cooking using biomass has been identified as a major cause of respiratory illnesses, resulting in four million premature deaths every year. Improved biomass cookstoves may help mitigate this challenge. This paper presents a two-dimensional axisymmetric steady-state computational fluid dynamics (CFD) model of a biomass burning, natural draft rocket cookstove. The CFD model includes coupled sub-models representing combustion, turbulence, and heat transfer. The model is validated against experimental data and used to predict temperatures and flow inside the cookstove, including the airflow rate through the cookstove and heat transfer to the cookpot. We find that the excess air is typically many times stoichiometric air during standard operating conditions and is sensitive to flow field obstructions. We analyze the effects of geometric and operational features such as the pot support height, secondary air entrainment, cone-deck shape, and baffle placement within the cookstove on the flow, airflow rate, mixing, and stove thermal efficiency. The model shows that secondary air entrainment, though ineffective by itself, increases turbulent mixing when used in conjunction with a central baffle but reduces thermal efficiencies due to enhanced heat transfer to the walls. We find that a lower pot support height decreases the airflow rate and increases thermal efficiency. We model thirty-six cone-deck configurations and find that the cone-deck shape primarily affects the airflow rate through the stove, with more constricted designs leading to higher thermal efficiencies.

09 BIOMASS FUELS↗
DOE OSTI2016

Reducing ultrafine particle emissions using air injection in wood-burning cookstoves

In order to address the health risks and climate impacts associated with pollution from cooking on biomass fires, researchers have focused on designing new cookstoves that improve cooking performance and reduce harmful emissions, specifically particulate matter (PM). One method for improving cooking performance and reducing emissions is using air injection to increase turbulence of unburned gases in the combustion zone. Although air injection reduces total PM mass emissions, the effect on PM size-distribution and number concentration has not been thoroughly investigated. Using two new wood-burning cookstove designs from Lawrence Berkeley National Laboratory, this research explores the effect of air injection on cooking performance, PM and gaseous emissions, and PM size distribution and number concentration. Both cookstoves were created using the Berkeley-Darfur Stove as the base platform to isolate the effects of air injection. The thermal performance, gaseous emissions, PM mass emissions, and particle concentrations (ranging from 5 nm to 10 μm in diameter) of the cookstoves were measured during multiple high-power cooking tests. Finally, the results indicate that air injection improves cookstove performance and reduces total PM mass but increases total ultrafine (less than 100 nm in diameter) PM concentration over the course of high-power cooking.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

How many replicate tests do I need?$-$ Variability of cookstove performance and emissions has implications for obtaining useful results

Almost half of the world’s population still cooks on biomass cookstoves of poor efficiency and primitive design, such as three stone fires (TSF). Emissions from biomass cookstoves contribute to adverse health effects and climate change. A number of “improved cookstoves” with higher energy efficiency and lower emissions have been designed and promoted across the world. During the design development, and for selection of a stove for dissemination, the stove performance and emissions are commonly evaluated, communicated and compared using the arithmetic average of replicate tests made using a standardized laboratory-based test, commonly the water boiling test (WBT). However, published literature shows different WBT results reported from different laboratories for the same stove technology. Also, there is no agreement in the literature on how many replicate tests should be performed to ensure “significance” in the reported average performance. This matter has not received attention in the rapidly growing literature on stoves, and yet is crucial for estimating and communicating the performance of a stove, and for comparing the performance between stoves. We present results of statistical analyses using data from a number of replicate tests of performance and emission of the Berkeley-Darfur Stove (BDS) and the TSF under well-controlled laboratory conditions. We observed moderate variability in the test results for the TSF and BDS when measuring several characteristics. Here we focus on two as illustrative: time-to-boil and PM2.5 (particulate matter less than or equal to 2.5 micrometers in diameter) emissions. We demonstrate that interpretation of the results comparing these stoves could be misleading if only a small number of replicates had been conducted. We then describe a practical approach, useful to both stove testers and designers, to assess the number of replicates needed to obtain useful data. Caution should be exercised in attaching high credibility to results based on only a few replicates of cookstove performance and emissions. Stove designers, testers, program implementers and decision makers should all benefit from improved awareness of the importance of adequate number of replicates required to produce practically useful test data.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2022

Retrofitting stoves with forced jets of primary air improves speed, emissions, and efficiency: Evidence from six types of biomass cookstoves

Incorporating jets of forced air into biomass cookstove combustion has been shown to potentially decrease harmful emissions, leading to a variety of designs in recent years. These have shown mixed success in terms of real-world performance, usability, and durability. The Jet-Flame forced draft retrofit accessory was recently developed to implement forced jets of primary air at a low cost into a wide range of types of cookstoves using a small 1.5-W fan housed in a low-cost cast iron body to be inserted beneath the fuel bed of a biomass cooking fire. This research sought to quantify the potential efficiency and emissions performance impacts of the Jet-Flame when installed in six different types of biomass cookstoves (three open or shielded fires and three rocket stoves) versus the natural draft performance of each. The effect of the operating fan voltage was also measured. A series of tests following a modified ISO 19867-1:2018 protocol were performed in the laboratory using the Aprovecho Laboratory Emissions Measurement System (LEMS) equipped with additional oxygen and temperature sensors. Results for each stove carefully tended with a single layer of sticks showed that the global average PM 2.5 reduction with the Jet-Flame was 89 % relative to the natural draft cases, with larger relative improvements seen in the most rudimentary stoves. CO was reduced by a global average of 74 %, reaching tier 4 or 5 for all stoves. Thermal efficiency was also improved by 34 % when calculated without taking into account the energy content of the remaining char (or 21 % with char), illustrating the value of burning char to provide cooking energy rather than leaving it unburned in the combustion chamber as is common in many natural draft stoves. Time to boil was also reduced by 8 %. In addition, adjusting the voltage of the jet-flame assisted in modulating firepower, improving the usability of the stove. These results indicate a strong potential for the Jet-Flame to help reduce emissions and fuel consumption in a wide range of cookstove designs at a relatively low cost or need for changes in behavior, fuel, or cooking device. The unit also provides enhanced usability in terms of ease of startup, cooking speed, low PM emissions at high power, and burning char. Additional studies are needed to measure performance in the field and under a variety of operational conditions.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

Achieving Tier 4 Emissions in Biomass Cookstoves

Previous literature on top-lit updraft (TLUD) gasifier cookstoves suggested that these stoves have the potential to be the lowest emitting biomass cookstove. However, the previous literature also demonstrated a high degree of variability in TLUD emissions and performance, and a lack of general understanding of the TLUD combustion process. The objective of this study was to improve understanding of the combustion process in TLUD cookstoves. In a TLUD, biomass is gasified and the resulting producer gas is burned in a secondary flame located just above the fuel bed. The goal of this project is to enable the design of a more robust TLUD that consistently meets Tier 4 performance targets through a better understanding of the underlying combustion physics. The project featured a combined modeling, experimental and product design/development effort comprised of four different activities: Development of a model of the gasification process in the biomass fuel bed; Development of a CFD model of the secondary combustion zone; Experiments with a modular TLUD test bed to provide information on how stove design, fuel properties, and operating mode influence performance and provide data needed to validate the fuel bed model; Planar laser-induced fluorescence (PLIF) experiments with a two-dimensional optical test bed to provide insight into the flame dynamics in the secondary combustion zone and data to validate the CFD model; Design, development and field testing of a market ready TLUD prototype. Over 180 tests of 40 different configurations of the modular TLUD test bed were performed to demonstrate how stove design, fuel properties and operating mode influences performance, and the conditions under which Tier 4 emissions are obtainable. Images of OH and acetone PLIF were collected at 10 kHz with the optical test bed. The modeling and experimental results informed the design of a TLUD prototype that met Tier 3 to Tier 4 specifications in emissions and Tier 2 in efficiency. The final prototype was field tested in India.

09 BIOMASS FUELS↗
DOE OSTI2018

Multidisciplinary Design of an Innovative Natural Draft, Forced Diffusion Cookstove for Woody and Herbaceous Biomass Fuels in East Africa

The goal of the project was to develop a commercially viable, natural draft cookstove that exceeds ISO tier 4 criteria while meeting the needs of rural and urban cooks in East Africa. The cookstove should be market ready that meets the manufacturing cost and usability expectations of the final users, including durability, safety, comfort, aspirational value and compatibility with local fuels, foods, and customs. The cleaner burning cookstove product was designed to replace open fires and inefficient stoves so that it can enhance indoor air quality, personal health, livelihoods, and the environment. The stove was developed using integrated and multidisciplinary design approach that included field based user research and focus groups, empirically verified computational fluid dynamics and heat transfer modeling, lab and field based emission and efficiency measurements, design for manufacturability, as well as in-home user product evaluations.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

Optimization of Secondary Air Injection in a Wood-Burning Cookstove: An Experimental Study

Nearly 40% of the world's population regularly cooks on inefficient biomass stoves that emit harmful airborne pollutants, such as particulate matter (PM). Secondary air injection can significantly reduce PM mass emissions to mitigate the health and climate impacts associated with biomass cookstoves. However, secondary air injection can also increase the number of ultrafine particles emitted, which may be more harmful to health. This research investigates the effect of secondary air injection on the mass and size distribution of PM emitted during solid biomass combustion. An experimental wood-burning cookstove platform and parametric testing approach are presented to identify and optimize secondary air injection parameters that reduce PM and other harmful pollutants. Size-resolved measurements of PM emissions were collected and analyzed as a function of parametric stove design settings. The results show that PM emissions are highly sensitive to secondary air injection flow rate and velocity. Although increasing turbulent mixing (through increased velocity) can promote more complete combustion, increasing the total flow rate of secondary air may cause localized flame quenching that increases particle emissions. As a result, biomass cookstoves that implement secondary air injection should be carefully optimized and validated to ensure that PM emission reductions are achieved throughout the particle size range.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Performance comparison of charcoal cookstoves for Haiti: Laboratory testing with Water Boiling and Controlled Cooking Tests

Charcoal cooking accounts for a large portion of Haiti's energy usage and leads to severe economic, health, and environmental hardships. Organizations are hoping that fuel-efficient cookstoves can help solve the problem. In this study, four charcoal cookstoves intended for dissemination in Haiti were rigorously assessed and compared using Water Boiling and Controlled Cooking Tests. Due to the poor thermal efficiency of the traditional stove, all improved stoves saved fuel on average over the traditional with the majority also reducing the total emissions released. However, the traditional stove could be difficult to replace because it had the fastest time-to-boil, an important consideration for end users. Here, through the testing, the number of trials conducted was found to be an important consideration for error analysis. Also, noticeable differences in stove performance were seen between the two protocols, supporting arguments by prior researchers of the necessity to use multiple test protocols for practically useful comparisons.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

Differential exposure and acute health impacts of inhaled solid-fuel emissions from rudimentary and advanced cookstoves in female CD-1 mice

Highlights: • Mice inhaled emissions from advanced cookstoves (CS) and a 3-stone (3-S)-fire. • Tier 2 and 3 CS emitted significantly less particulate matter and carbon monoxide. • 3-S fire (Tier 0)-exposed mice were the only group to develop acute lung injury. • Diminished macrophage phagocytosis was observed in Tier 2 CS-exposed mice. • Lung glutathione was significantly depleted across all Tier 0–3 CS-exposed mice. There is an urgent need to provide access to cleaner end user energy technologies for the nearly 40% of the world's population who currently depend on rudimentary cooking and heating systems. Advanced cookstoves (CS) are designed to cut emissions and solid-fuel consumption, thus reducing adverse human health and environmental impacts.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

Performance of Charcoal Cookstoves for Haiti, Part 2: Results from the Controlled Cooking Test

Five charcoal cookstoves were tested using a Controlled Cooking Test (CCT) developed from cooking practices in Haiti. Cookstoves were tested for total burn time, specific fuel consumption, and emissions of carbon monoxide (CO), carbon dioxide (CO 2 ), and the ratio of carbon monoxide to carbon dioxide (CO/CO 2 ). These results are presented in this report along with LBNL testers’ observations regarding the usability of the stoves.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2010

Quantification of Black Carbon and Other Pollutant Emissions from a Traditional and an Improved Cookstove

Traditional methods of cooking in developing regions of the world emit pollutants that endanger the lives of billions of people and contribute to climate change. This study quantifies the emission of pollutants from the Berkeley-Darfur Stove and the traditional three-stone fire at the Lawrence Berkeley National Laboratory cookstove testing facility. The Berkeley-Darfur Stove was designed as a fuel efficient alternative to the three-stone fire to aid refugees in Darfur, who walk long distances from their camps and risk bodily harm in search of wood for cooking. A potential co-benefit of the more fuel efficient stove may be reduced pollutant emissions. This study measured emissions of carbon dioxide, carbon monoxide, particulate matter, and sunlight-absorbing black carbon. It also measured climate-relevant optical properties of the emitted particulate matter. Pollutant monitors were calibrated specifically for measuring cookstove smoke.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Technology Innovations to Improve Biomass Cookstoves to Meet Tier 4 Standards

Technology Innovations to Improve Biomass Cookstoves to Meet Tier 4 Standards. Protecting public health has become a major motivation for investigating how improved cook stoves might function as a viable intervention. Currently, the great majority of cookstoves for sale in the developing world were not designed for this purpose but instead success was based on criteria such as reduced fuel use, affordability, and ease of use. With DOE funding Aprovecho Research Center spent three years creating stoves using an iterative development and modeling approach resulting in four stoves that in lab tests met the World Health Organization (2014) intermediate rate vented targets for PM2.5 and for CO.

09 BIOMASS FUELS↗
DOE OSTI2011

Biomass Cookstoves Technical Meeting. Summary Report

In regions where biomass is a traditional fuel for cooking, improved cookstoves can enhance indoor air quality, personal health, livelihoods, and the environment—while substantially reducing greenhouse gas (GHG) emissions. Although ongoing efforts have successfully disseminated improved stoves that achieve many of these benefits, substantially greater emissions reductions are needed to comply with international guidelines for indoor air quality and to limit GHG emissions like black carbon.

Biomass↗
DOE OSTI2010

Trading Carbon: Can Cookstoves Light the Way (LBNL Science at the Theater)

Science at the Theater: Get smart about carbon! Learn how families in Africa, using stoves designed by Berkeley Lab, are at the forefront of global carbon reduction. Ashok Gadgil is the driving force behind the Berkeley-Darfur Cookstove. He is a researcher, inventor, renowned humanitarian, and director of Berkeley Lab's Environmental Energy Technologies Division. Kayje Booker is a Berkeley Lab researcher and UC Berkeley graduate student in ecosystem sciences. She is exploring how carbon markets can serve as catalysts for innovation in technologies for the poor. Adam Rausch is a Berkeley Lab researcher and UC Berkeley graduate student in civil environmental engineering. He helps to design and test stove designs in Ethiopia and elsewhere.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2010

Carbon Smackdown: Cookstoves for the developing world

In this June 30, 2010 Berkeley Lab summer lecture, learn how efficient cookstoves for the developing world — from Darfur to Ethiopia and beyond — are reducing carbon dioxide emissions, saving forests, and improving health. Berkeley Lab's Ashok Gadgil, Kayje Booker, and Adam Rausch discuss why they got started in this great challenge and what's next.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗