Wood Boilers Research Articles

The Impact of Climate Change and Window Parameters on Energy Demand and CO2 Emissions in a Building with Various Heat Sources

This article presents an original study on the impact of climate change and the area of windows Awi (factor X1), the thermal transmittance coefficient of windows Uwi (factor X2), and the coefficient of total solar transmittance factor of the glazing ggl (factor X3) on the index of annual usable energy demand for heating EUH (function Y) of a single-family residential building in the climatic conditions of Bialystok (Poland), which were loaded with an equal gradual increase in average monthly external temperature by Δθe,n (factor X4). Based on the results of the computational experiment, a deterministic mathematical model of this dependence was developed, and the effects of selected factors on the Y function were analyzed for the considered climatic conditions. Moreover, in cases of selected variants, the influence of the energy source on the amount of final energy used and CO2 emissions was studied. It was found that an increase in the average monthly external temperature reduces the EUH of the tested building by 8.4% per every 1 °C of increase in Δθe,n. The reduction in CO2 emissions as a result of climate change is visible for systems with low efficiency and high emission factors (wood boiler), while in the case of pro-ecological high-efficiency systems (with a ground-source pump heat) it is inappreciable. Due to the need to decarbonize buildings, knowledge about the impact of the properties of windows, which are the weakest element in terms of heat loss through the building envelope, as well as the type of heat source on heat demand and CO2 emissions, is very important for engineers and designers when making the correct decisions.

Attitudes and perceptions of wood energy technologies in the Great Lakes region, USA

This paper explores social acceptance of different wood-based energy applications in the Great Lakes region in the Upper Midwest, USA. Specifically, the paper examines attitudes and perceptions towards residential wood burning, commercial-scale wood boilers for heat, combined heat and power (CHP) facilities, and industrial power generation in Michigan. In 2021, we conducted a state-wide survey (n = 207) and 30 semi-structured interviews with individuals representing different stakeholder perspectives, including regulatory agencies, biomass industry leaders, non-governmental organizations and scientists who have shaped biomass debates, forest products workers, and Michigan residents. Results suggest that the depth of an individual's knowledge about different types of wood energy applications generally led to more positive attitudes, particularly for smaller-scale uses of wood for heat. Despite perceived environmental, economic, and human health risks of using wood for different energy applications, across all stakeholder groups, 70% of respondents perceived environmental benefits, 61% perceived economic benefits, and 57% perceived health benefits. Changing economic and environmental conditions in different parts of the state contributed to people's attitudes toward different forms of wood energy and their perceptions of associated risks and benefits. A key recommendation of this study is that policy-makers and energy developers seek to understand the complex factors that influence social acceptance when planning for the adoption of new types of wood-based bioenergy technologies.

Four approaches for the year-round operation of wood-fired heating plants with low pollutant emissions

Fluctuations in heat demand and low heat demand in summer make it difficult to operate wood boilers all year round at high efficiency and low pollutant emissions. Therefore, today's wood-fired heating plants are often equipped with an auxiliary fossil fuel boiler. This paper investigates technical approaches to operate wood heating plants without additional fossil heat while avoiding unfavorable operation with high pollutant emissions. To evaluate these concepts, the dynamic behavior of wood-fired heating plants is modelled. The model includes one to four wood boilers, an auxiliary fossil fuel boiler, the heat demand, a stratified heat storage tank and the control system. The simulation reveals that the fossil share can be eliminated by large boiler output ranges and the use of several wood boilers in cascade. High storage capacities and large boiler output ranges enable low pollutant emissions and low cool down losses of the wood boilers. By doubling the storage capacity from 30 to 60 min of the nominal boiler output, reductions of the annual emissions of carbon monoxide and particulate matter of 17% and 8% are observed. Mitigating heat demand peaks can reduce pollutant emissions of heating plants with small storage capacity.

Study of the memory effect of PCDD/F during the combustion of several biomasses in a moving grate boiler.

The objective of this work was to study the influence of temperature on the PCDD/Fs behavior stored in biomass ashes issued from an automatic pilot-scale wood boiler. A mixture of these ashes with a dioxin mass ratio dry based of 5.9 μg kg-1 was used for thermal treatment at temperatures ranging between 200 and 500°C. First tests were carried out in a macro thermogravimetric analysis instrument while a couple of other tests were carried out in a quartz-lined crossed fixed-bed reactor. These treated ashes were afterwards analyzed and their dioxin mass ratio was determined. Results obtained from these both experiments are radically different: ashes treated in macro-TGA contain 18 times more PCDD/Fs than the initial non-treated ashes while those from the reactor have 84% less of PCDD/Fs. Ninety-one percent of stored PCDD/Fs in the initial ashes were eliminated after 1h at 400°C in crossed fixed-bed reactor. Macro-TGA experiments are a representation of what happens during the shutdown and cooling phase of the boiler, some areas reaching temperatures for which the formation of PCDD/Fs is optimal. Without cleaning the boiler, a memory effect on further tests is observed.

화목보일러 연통 과열 화재위험성에 관한 연구

Recently, economic downturn and the era of ultra-high oil prices caused by the global pandemic, demand for the installation of wood boilers in home or rural houses is increasing as a means of reducing heating costs in winter. In general, wood boilers, which have been used a lot in factories and warehouses, not only reduce the burden of heating costs, which account for a large part of household spending in winter, but also are simple and economical, so the demand is gradually increasing. However, due to the nature of the fuel, it is difficult to control the fire power, and there is no accurate installation manual, so there is a high possibility of fire, such as overheating of the stovepipe and splashing on nearby combustibles. In addition, there are many problems that were not initially expected during the manufacture and installation of the wood boiler due to legal defects. This study aims to analyze fire hazards according to communication structure, material, and boiler room construction materials by conducting fire re-experiments based on fire cases by wood boilers, and provide basic data for safe installation and use of fire boilers.

薪ボイラを用いたスターリングエンジン発電システムの開発研究

A heat and power supply system is constructed by connecting a 1kW class Stirling engine generator and a wood-fired boiler. First, a performance evaluation test of the wood boiler was conducted to determine the amount of wood input. It was found that combustion gas temperature required to drive the Stirling engine generator was more than 600°C, and that 19 kg of firewood per hour was needed to meet this requirement. Based on this result, a power supply system test was conducted, but no power output could be obtained. Therefore, the chimney was installed in an L-shaped position on the back of the wood boiler to improve the combustion gas flow. The improved wood boiler was tested again, so that the power output of 151 W and the heat output of 36.5 kW were obtained, and the energy utilization efficiency of this system was approximately 60%.

Comparison of Ashes Produced in a Biomass Moving Grate Boiler by Wood Chips and Sewage Sludge

One option to fight global warming is to convert our use of fossil energy into renewables such as biomass energy. However, the forest preservation and the quality of the ambient air are also two major issues. Therefore, the use of biomass waste without any supplementary emissions could represent a part of the solution. In this study, two fuels were considered for a 200 kW moving grate boiler. A multicyclone and a bag filter were fitted on the boiler. The first fuel consisted of classical wood chips whereas the second was a mixture of wood chips with sewage sludge. This second fuel presented a high ashes mass ratio compared to wood chips. The aim was to verify the possibility to burn this kind of fuel without any modification of the installation. The first relevant result is that the conventional pollutants, i.e., CO and NOx, remained under the emissions limits even with the sewage sludge combustion. The Total Suspended Particles emissions at the exhaust were always under 5.4 mg·Nm−3 dry based corrected at 6% of O2, which is low with respect to the standard limitation. The majority of the ashes remained on the combustion room. However, with both fuels, about 5% of ashes mass remained in the heat exchanger. Nevertheless, the heat exchanger was more clogged with the second fuel, which produced five time more ashes. This may lead to a yield loss. Thus, sewage sludge can be used in a wood boiler without any issue if an automatic exchanger sweep is fitted on the installation.

Emission Reduction Potential of Different Types of Finnish Buildings through Energy Retrofits

Energy retrofitting of buildings shows great potential in reducing CO2 emissions. However, most retrofitting studies only focus on a single building type. This paper shows the relative potential in six Finnish building types, to identify possible focus areas for future retrofits in Finland. Data from previous optimization studies was used to provide optimal cases for comparison. Energy demand of the buildings was generated through dynamic simulation with the IDA-ICE software. The cases were compared according to emissions reduction, investment and life cycle cost. It was found that, in all buildings, it was possible to reduce emissions cost-neutrally by 20% to 70% in buildings with district heating and by 70% to 95% using heat pumps. Single-family homes with oil or wood boilers switching to heat pumps had the greatest emission reduction potential. More stringent requirements for energy efficiency could be mandated during building renovation.

Doubling the power of a wood boiler with fixed grill

The article presents one technological modality of doubling the thermal power of a wood boiler. The base of departure is a wood boiler with fixed grill with a power of 30 kW and a yield of 62%. The technological variant is to increase with maximum 50% of the value of the heat transfer surfaces and modify the water circuit. For this, a FEM thermal transfer simulation program was used. In the first part of the article is presented the initial 30 kW wood boiler with the heat transfer surfaces. With the help of the FEM program, a thermal transfer simulation was performed. The results of the program were compared with those of the technical characteristics of the wood boiler. The authors of the article carried out different simulations with new surface types, changes in the water circuit, heat transfer calculations, fluid flow angles, so that the efficiency reaches over 75%. The design results were put into practice and the new wood boiler was built. The power of the wood boiler reached a maximum of 75 kW. The article presents some of the intermediate stages of execution. The wood boiler was tested in a specialized installation. It can be seen that the efficiency increased by 18%, from 62 to 80 and the thermal power reaches a maximum of 75 kW. The hot water flow is about 60 l / min, a very good value considering the type of wood boiler. Using the experimental results presented in this paper, wood boilers can be designed with much smaller dimensions having the same characteristics of power and water flow.

A Critical Review of Comminution Technology and Operational Logistics of Wood Chips

This review offers essential information on the factors affecting the efficiency of wood chip supply chains, and of comminution in particular. The paper indicates the pros and cons of alternative set ups, as well as the impact of specific technical choices, including machine setup and adjustments. Chipping performance is closely related to chipper characteristics and setup, and to feedstock type. In general, productivity is directly proportional to chipper power and piece size, as far as the latter is within the capacity of the machine in question. Blade wear, cut length, and screen size also have a strong impact on productivity and work quality—and so do operator experience, skill, and motivation. Daily production is affected by work organization and machine reliability: delay time may represent between 25 and 50% of actual work site time—occasionally more, especially when the interface with the transport fleet is not properly managed. Wood biomass supply chains are characterized by comminution as their central process, since all automatic wood boilers require comminuted wood. Different supply chains are defined by what kind of feedstock is comminuted and where comminution takes place. In principle, one can comminute whole trees, logs, or logging residues—and comminution can occur on the cutover, at the landing or in a yard—be it a terminal or the factory wood yard. Comminution can be obtained by chipping, grinding, crushing, or shredding. Chipping is by far the most common method and is applied in different ways depending on work conditions.

Mutagenicity- and pollutant-emission factors of pellet-fueled gasifier cookstoves: Comparison with other combustion sources

Emissions from solid-fuel burning cookstoves are associated with 3 to 4 million premature deaths annually and contribute significantly to impacts on climate. Pellet-fueled gasifier stoves have some emission factors (EFs) approaching those of gas-fuel (liquid petroleum gas) stoves; however, their emissions have not been evaluated for biological effects. Here we used a new International Organization for Standardization (ISO) testing protocol to determine pollutant- and mutagenicity-EFs for a stove designed for pellet fuel, the Mimi Moto, and for two other forced-draft stoves, Xunda and Philips HD4012, burning pellets of hardwood or peanut hulls. The Salmonella assay-based mutagenicity-EFs (revertants/megajouledelivered) spanned three orders of magnitude and correlated highly (r = 0.99; n = 5) with EFs of the sum of 32 particle-phase polycyclic aromatic hydrocarbons (PAHs). The Mimi Moto/hardwood pellet combination had total-PAH- and mutagenicity-EFs 99.2 and 96.6% lower, respectively, compared to data published previously for the Philips stove burning non-pelletized hardwood, and 100 and 99.8% lower, respectively, compared to those of a wood-fueled three-stone fire. The Xunda burning peanut hull pellets had the highest fuel energy-based mutagenicity-EF (revertants/megajoulethermal) of the pellet stove/fuel combinations tested, which was between that of diesel exhaust, a known human carcinogen, and a natural-draft wood stove. Although the Mimi Moto burning hardwood pellets had the lowest fuel energy-based mutagenicity-EF, this value was between that of utility coal and utility wood boilers. This advanced stove/fuel combination has the potential to greatly reduce emissions in contrast to a traditional stove, but adequate ventilation is required to approach acceptable levels of indoor air quality.

Investigation of real-life operating patterns of wood-burning appliances using stack temperature data

ABSTRACTA study was undertaken to identify patterns of consumer use of outdoor wood boilers or outdoor wood furnaces (technically referred to as outdoor wood-fired hydronic heaters (OWHHs)) and indoor wood stoves (IWSs) to inform the development of performance testing protocols that reflect real-life operating conditions. These devices are manually fed, and their usage protocols are a function of a number of variables, including user habits, household characteristics, and environmental factors. In this study, researchers logged the stack wall temperatures of 4 OWHH and 20 IWS units in the states of New York and Washington over two heating seasons. Stack wall temperature is an indicator of changes in combustion modes. Two algorithms were developed to identify usage modes and cold and warm start refueling events from the stack wall temperature time series. A linear correlation analysis was conducted to evaluate the effect of heat demand on usage patterns. The results and methods presented here will inform the cataloging of typical operational patterns of OWHHs and IWSs as a step in the development of performance testing procedures that represent actual in-home usage patterns.Implications: Current US regulatory programs for residential wood heating use a certification program to assess emissions and efficiency performance. Testing under this program uses a test that burns 100% of a single, standardized wood fuel charge to assess performance at different steady-state load conditions. This study assessed in-field operational patterns to determine if the current certification approach accurately characterized typical homeowner use patterns. The data from this study can be used to inform revisions to testing methods to increase certification test comparability between lab and field performance.

Local stability analysis of an irreversible absorption refrigerator powered by a wood boiler

• We analyse the local stability of an irreversible absorption refrigerator powered by a waste wood boiler. • The coefficient of performance COP is taken as objective functions. • We derive the expressions of the relaxation times at the optimal steady-state of the maximum coefficient of performance . • We discuss the effects of some performance parameters on relaxation times. This paper in refrigeration analyses the effects of internal and external irreversibilities on the steady-state of a double irreversible absorption refrigeration system powered by a waste wood boiler. At the optimal steady-state of the maximum coefficient of performance, expressions of relaxation times of a double irreversible absorption refrigerator are derived. The influence of internal irreversibility parameters, heat leakage coefficient and heat transfer coefficients on relaxation times are discussed. Phase portraits for the trajectories are presented. The results of our analysis show that the eigen-values of the generator-absorber assembly are real with opposite signs while those of the evaporator-condenser are real and both negative. From these results, it follows that internal and external irreversibilities parameters have a draconian effect on the steady-state of the generator-absorber assembly which leads to the disturbance of the absorption system and consequently to its instability. The result can provide some theoretical guidelines for the designs of real absorption refrigerators.

How Are Wood and Non-Wood Forest Products Utilized in the Czech Republic? A Preliminary Assessment of a Nationwide Survey on the Bioeconomy

The Czech forests occupy 33.7% of the total country area; thus, wood and non-wood forest products (NWFPs) are important resources for the country. To date, the country has not adopted a forest bioeconomy strategy. A forest bioeconomy is defined as all activities that relate to the forest ecosystem services (FES). This study aimed to provide an initial evaluation regarding the use of forest products and related factors, and to make recommendations on developing wood consumption and promoting other FES for the adoption of a forest bioeconomy strategy in the country. The research study was part of a nationwide survey in June 2019. An online panel of 1050 respondents aged 18–65 years old was recruited based on a quota sampling procedure. Wood products were the most preferred material for furniture (96.3%) and building materials (46.3%). In total, 38.6% of Czech residents used wood as a source of energy, mostly in the form of firewood. It is challenging to switch the practice from using fossil-based heating to wood boiler energy source. The further development of wood into products with a high added value is recommended. Picking mushrooms and berries were among the popular activities in relation to NWFPs. The promotion of wood and NWFPs is encouraged, starting with increasing awareness and knowledge of the strength of the forest-based sector as a renewable energy resource and the importance of FES, using different channels as sources of information.

Comparison of heating system alternatives for a rural house employing analytic hierarchy process

In this study were analyzed different heating systems to select the most appropriate type for a rural house. The performances of each alternative have been evaluated and compared using the analytic hierarchy process (AHP), a well-known and widely used multi-criteria method. There were considered five heating options: wood boiler, electric boiler, gas boiler, pellet boiler, and electric heating carpet, which were combined with two different heating terminals: radiant floor heating and the classic radiator. The alternatives were analyzed based on several criteria, which were defined considering economic, environmental, and social aspects. After the variants were ranked, and the most appropriate solution was determined, a sensitivity analysis was performed. The results indicated that the final ranking of the alternatives is robust, with slight variances, depending on the percentage with which the criteria weights were varied.

Environmental and Economic Benefits from the Phase-out of Residential Oil Heating: A Study from the Aosta Valley Region (Italy)

Although its use is declining, oil heating is still used in areas not covered by the methane grid. Oil heating is becoming more and more expensive, requires frequent tank refill operations, and has high emissions of greenhouse gas (GHG) and air pollutants such as SOx. In addition, spills from oil underground storage tanks (USTs) represent a serious environmental threat to soil and groundwater quality. In this paper, we present a comprehensive analysis on technical alternatives to oil heating with reference to the Aosta Valley (NW Italy), where this fuel is still often used and numerous UST spills have been reported in the last 20 years. We assess operational issues, GHG and pollutant emissions, and unit costs of the heat produced for several techniques: LPG boilers, wood boilers (logs, chips, pellets) and heat pumps (air-source, geothermal closed-loop and open-loop systems). We examine the investment to implement such solutions in two typical cases, a detached house and a block of flats, deriving payback times of about 3–8 years. Wood log boilers turn out to be the most economically convenient solutions; however, heat pumps provide several benefits from the operational and environmental points of view. In addition, including solar thermal panels for domestic hot water or a photovoltaic plant would have payback times of about 6–9 years. The results highlight the economic feasibility and the multiple benefits of a rapid phase-out of oil heating in Italy.

Comparative analysis of different heating systems based on the surface area of a household

The scope of this paper was to determine if the efficiency of a heating system depends on the surface area of a household and to identify the surface intervals for which a heating system is most appropriate than others. There were considered nine alternatives for the analysis: five different heating sources (wood boiler, electric boiler, gas boiler, pellet boiler and electric heating carpet) combined with two different heating terminals (radiant floor heating and the classic radiator), which were evaluated based on initial investment, fuel cost and the total annual expenditure for each heating system. The results indicated that the type of heating system for a household might vary depending on its surface, considering the three comparison factors mentioned before.

A novel electrical charging condensing heat exchanger for efficient particle emission reduction in small wood boilers

Small-scale biomass combustion is an important source of fine particles in ambient air, causing adverse health and environmental effects. Thus, there is a clear need to develop efficient and feasible flue gas cleaning technologies for small-scale combustion appliances. In this study a novel electrical charging condensing heat exchanger (eCHX) for combined fine particle removal and efficient heat recovery from flue gases was demonstrated in a small biomass-fired boiler. The method is based on the combination of a shielded corona charger and a condensing heat exchanger, where fine particles are removed by the electrophoretic, thermophoretic and diffusiophoretic forces. The eCHX was found to decrease >80% of fine particle mass (PM1) emissions and >40% of particle number emissions with simultaneous high thermal efficiency in the heat exchanger. The usage of the condensing heat exchanger without electrical charging resulted in 40% decrease in PM1 emissions when compared to the usage of a traditional tube heat exchanger. The advantage of the eCHX system is that it replaces the conventional heat exchanger in boilers, making it a compact and inexpensive solution, when compared to additional flue gas cleaning devices installed after the boiler.

Next generation cogeneration system for industry – Combined heat and fuel plant using biomass resources

The requirement for sustainable development has prompted the researchers to explore solutions for better utilization of renewable energy resources in the future. Biomass is a promising resource and it can be converted to multiple products and services including fuels, chemicals, heat and electricity via different conversion routes. Hence, replacement of fossil-based services with biomass-based services is critical to mitigate fossil CO2 emissions, and innovative design of new and efficient energy conversion systems is necessary. Different industries need heat for their operations at different temperature levels. Today, these demands are satisfied using conventional natural gas boilers by imposing a CO2 tax to account for their emissions. In this study, we discuss the potential of replacing conventional boilers with a combined heat and fuel (CHF) plant design which utilizes lignocellulosic biomass in thermochemical conversion to generate heat for different industrial sectors together with biofuels cogeneration. Heat is generated due to the exothermic nature of the thermochemical conversion processes that operate at high temperatures. Gasification process produces syngas which is converted into fuels such as synthetic natural gas, Fischer-Tropsch crude, methanol and dimethyl ether and electricity. Different scenarios are evaluated considering the CO2 produced via this system is either released, sequestrated, or stored and used in a co-electrolysis unit in which surplus renewable electricity available during summer is converted into additional syngas. A parametric analysis has been performed considering type and size of plants, CO2 tax, and purchase and transportation costs of wood to compare the price of heat for the industrial sectors. Natural gas and wood boilers are used as the basis to calculate the breakeven CO2 tax values for the same heat prices for the proposed CHF systems. The results of this study present a state-of-the-art renewable energy system as an alternative to conventional boilers.

A Simple Method to Determine Cytotoxicity of Water-Soluble Organic Compounds and Solid Particles from Biomass Combustion in Lung Cells in Vitro.

Adverse health effects of condensable organic compounds (COC) and potential secondary organic aerosols from wood combustion emissions are difficult to determine. Hence, available information is usually limited to a small number of specific applications. Therefore, we introduced a simple, fast, and economic method where water-soluble COC (WSCOC) and WSCOC together with water-soluble primary solid particles (WSpSP) from wood combustion were sampled and subsequently exposed to cultured human lung cells. Comparing the cell viability of H187 human epithelial lung cells from five combustion devices, operated at different combustion conditions, no, or only a minor, cytotoxicity of WSCOC is found for stationary conditions in a grate boiler, a log wood boiler, and a pellet boiler. All combustion conditions in a log wood stove and unfavorable conditions in the other devices induce, however, significant cytotoxicity (median lethal concentration LC50 5-17 mg/L). Furthermore, a significant correlation between CO and cytotoxicity was found ( R2 ∼ 0.8) suggesting that the simply measurable gas phase compound CO can be used as a first indicator for the potential harmfulness of wood combustion emissions. Samples containing WSCOC plus WSpSP show no additional cytotoxicity compared to samples with COC only, indicating that WSCOC exhibit much higher cytotoxicity than WSpSP.