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Abstract: The performance of a spark ignition internal combustion engine (SI ICE) fueled with biomass gas (woodgas) is evaluated using an analytical mathematical model. For the evaluation, the model was based on the fuel-air thermodynamic cycle for spark ignition engines, taking into account the composition of woodgas used as fuel, the thermodynamic properties of the fuel supplied, the cylinder geometric characteristics, the engine operational conditions, the effects of heat losses in the cycle through the walls of the cylinders and due to the loss as gas “blow-by”, the influence of dissociation processes during the combustion and the residual gases remaining in the cylinders at the beginning of the compression stroke. The model can predict of the internal temperatures profiles, heat flow, as well as the work and pressure in relation to crank angle. It was used also to evaluate the influence of the rotation speed, the air ratio and the ignition timing on the engine indicated power. It was found that when feeding the engine with woodgas, a power output between 59 and 65% can be obtained, in comparison it's powered by gasoline. Additionally, the analysis shown the engine performance when feeding it with pure methane (100%), to give an idea about what would happen if the same engine is fueled with natural gas under the same conditions (the main component of natural gas is methane and the presence of this in composition generally varies between 70 and 95%). [Copyright &y& Elsevier]

Abstract: Biomass downdraft reactors, coupled with reciprocating internal combustion engines (RICEs), are a viable technology for small scale heat and power generation. This paper contains information gathered from a review of published papers on the effects of the particle size and the moisture content of biomass feedstock and the air/fuel equivalence ratio used in the gasification process with regard to the quality of the producer gas. Additionally, data on the parameters of producer gas, such as its energy density, flame speed, knock tendency, auto-ignition delay period and the typical spark ignition timing, are systematised. Finally, information on the typical performance of various diesel and spark ignition RICEs fuelled with producer gas is presented. [Copyright &y& Elsevier]

Abstract: A mathematical model which was developed to predict steady state performance of a biomass downdraft gasifier/spark ignition engine power system is described. A mathematical model of the integrated system consists of two parts: the fixed bed downdraft gasifier and spark ignition internal combustion engine models. For calculations the gasifier is split into three zones, namely drying – pyrolysis, oxidation and reduction sections. The gasifier’s mathematical model consists of three separate sub-models, each describing the processes in the corresponding zone. The process taking place in the reduction zone has been described using chemical kinetic principles in order to avoid introduction of assumptions related to achievement of the thermo-chemical equilibrium state during gasifier’s operation. The model is capable to accurately predict molar concentrations of different species in syngas (CO2, CO, H2O, H2, CH4 and N2) and the temperature profile in the gasifier along its height. This information then can be used for sizing the reactor and material selection. The engine’s model is based on the fuel–air thermodynamic cycle for spark ignition engines and such model takes into account the composition of syngas used as fuel. The engine’s model also takes into account effects of heat losses in the cycle through the walls of the cylinders and due to the gas blow by. Finally, the influence of dissociation processes during the combustion and the residual gases remaining in the cylinders at the beginning of the compression stroke is accounted for computations of the engine’s performance. The numerical results obtained using the proposed model are in a good agreement with data produced with the use of other theoretical models and experimental data published in open literature and with experimental data obtained in these investigations. The proposed model is applicable for modelling integrated downdraft gasifier/engine biomass energy systems and can be used for more accurate adjustment of design parameters of the gasifier and the engine in order to provide the higher overall efficiency of the system. [Copyright &y& Elsevier]

Prefabricated concrete (PC) components require curing at the specific environment after being cast for the concrete to harden to the required levels over a certain period of time. Currently, steam curing is used as the major technique in concrete production. However, this method is highly energy consuming and requires large amounts of fossil fuels. Analysis of thermal process parameters in PC curing and thermal properties of phase change materials (PCMs), developed by the research team at Beijing University of Technology for the greenhouse applications, resulted in the development of the conceptual design of passive solar PC steam curing buildings with on-wall PCM heat storage. The process of selection of the PCM for installation on the inner surface of the main sun-facing wall of solar passive curing buildings is described. The selection is the result of the evaluation of suitable PCMs using the simultaneous process of transient energy consumption simulation with the deployment of EnergyPlus software and one-dimensional unsteady heat transfer modelling across the thickness of the thermal storage. The EnergyPlus simulations were calibrated against experimental data obtained in the curing building in Hebei Province, China. Theoretical simulations for such the building demonstrate that a GH-37 PCM panel with a thickness of 50 mm is suitable for such the application. The temperature range of phase transition for the GH-37 PCM is between 37.4 and 43.5 °C with latent heat equal to 227.5 kJ/kg. Compared to the same case but without PCM, the monthly and nocturnal average temperature of the inner surface of the main sun-facing wall increases by 1.3 °C and 2.7 °C, respectively. The heating load is reduced by 6.4, 5.8, 3.4 and 2.9 GJ in spring, autumn, summer and winter periods, respectively. The amount of annual steam consumption is reduced by 4.7%. • The design concept of solar-assisted PC curing room with PCM was proposed. • Mathematical model of the PC solar-assisted curing room with PCM was carried out. • The selection of a suitable PCM and its optimal thickness was carried out. • The proposed design solution provides annual energy saving of 4.7%. [ABSTRACT FROM AUTHOR]