Thermodynamic Properties of Real Porous Combustion Reactor under Diesel Engine-Like Conditions

Thermodynamic conditions of the heat release process under Diesel engine-like conditions in a real porous combustion reactor simulated in a special combustion chamber were analyzed. The same analyses were performed for a free volume combustion chamber, that is, no porous reactor is applied. A common rail Diesel injection system was used for simulation of real engine fuel injection process and mixture formation conditions. The results show that thermodynamic of the heat release process depends on reactor heat capacity, pore density, specific surface area, and pore structure, that is, on heat accumulation in solid phase of porous reactor. In real reactor, the gas temperature and porous reactor temperature are not equal influenced by initial pressure and temperature and by reactor parameters. It was found that the temperature of gas trapped in porous reactor volume during the heat release process is less dependent on air-to-fuel-ratio than that observed for free volume combustion chamber, while the maximum combustion temperature in porous reactor is significantly low. As found this temperature depends on reactor heat capacity, mixture formation conditions and on initial pressure. Qualitative behavior of heat release process in porous reactors and in free volume combustion chamber is similar, also the time scale of the process

Impact of the position of the window in the reveal of a cavity wall on the heat loss and the internal surface temperature of the head of an opening with a steel lintel

© 2017 Elsevier B.V. The interface between the head of the window and the wall represents one of the largest thermal bridges of a building and one of the areas with the highest risk of surface condensation. This paper confirmed the importance, and investigated the impact, of the location of the window in the reveal of a cavity wall on the Ψlintel and surface temperature of the area. Additionally, it studied the reliability and accuracy of assessing this thermal bridge using an adiabatic surface instead the actual window. Two possible construction details that meet PARTL 2013 were modelled and assessed with HEAT2D software, following two different methods: the standard and commonly used (adiabatic surface) method and the detailed one (including the actual window). The outputs revealed that the adiabatic surface prevents the software to account the heat transfer that in reality occurs between the window frame and the highly conductive steel lintel. Therefore, the current simplified method could underestimates the heat losses up to 33% and the surface temperature by over 4°C for certain locations. Additionally, it locates the optimal area for the frame between overlapping 70mm the cavity to align with the insulation layer of the cavity. Finally, it concluded that under current trends of extremely low Ψlintel the adiabatic surface has a greater impact than before, producing less accurate outputs, enough to start to think on the necessity of including the actual window during the assessment of the thermal performance of top hat lintels without base plate in low/zero carbon projects

Impact of current steel lintels on the thermal performance of cavity wall buildings under the elemental recipe of Part L1A 2013

This study investigates the impact of current steel lintels on the CO2 emissions of a notional building when trying to comply with the new PART L1A 2013 of the Building Regulations of England and Wales. For this purpose different families of lintels were assessed under SAP2009 using 12 different cavity walls with U-value under 0.18W/m K. Any of the current steel lintels without base plate studied in this research were found to be useable under PART L1A 2013. Their impact, depending also upon the construction detail used, could vary from 3% to 0.7% of the DFEES and from 1.6 to 0.4% of the DER of the notional building here studied.

Impact of the simplification of the methodology used to assess the thermal bridge of the head of an opening

© 2014 Published by Elsevier B.V. The interface between the head of the window and the wall represents one of the largest thermal bridges of a building and one of the areas with the highest risk of surface condensation and mould growth. This study is concerned with the reliability and accuracy of assessing this thermal bridge heat loss and surface temperature at the junction of a window with a specific steel lintel where the window frame itself is excluded from the thermal model. Four cases were modelled, covering the evolution of the construction details of this junction, following changes in British legislation in regards to U-values. They were assessed with HEAT2D software under the standard (simplified) method and a more detailed approach. The outputs revealed that replacing the window frame with an adiabatic surface during the modelling process (as per standard) underestimates the risks of mould growth or surface condensation (as per Part L1A 2010), especially if the window has a high U-value

Numerical simulation of the aerodynamic performance of a novel micro-aerial vehicle mimicking a locust

This paper describes the design, micro-fabrication and testing of a novel Micro-Aerial Vehicle (MAV) that mimicking a real locust. Actual parameters of locust insect are used to create a micro-scale MAV that can replace the traditional types that mimicking dragonfly and birds. Based on the obtained results, the novel MAV crucial parameters are its weight and strength to take-off under normal locust performance parameters fashion. Computational Fluid Dynamics (CFD) simulations are carried out at angles of attack of 10°, 20° and 30° and flapping frequencies of 19 Hz, 24 Hz, 30 Hz, 35 Hz and 40 Hz to investigate the aerodynamic performance of this designed MAV and optimize its flapping frequency. The simulation results defined the frequency at which the MAV is capable of hovering and take-off. In addition, the simulation results showed that the MAV is able to utilize some lift enhancement mechanisms that are being actually used by insects. These results enhances the manufacturing process of future MAV’s, especially in the material selection and manufacturing method, and the transmission mechanism for flight.Peer Reviewe