Study on the Leaves Densities as Parameter for Effectiveness of Energy Transfer on the Green Facade

This research involves the study of two models of green facades and a model of bare wall. A house miniature was used as thermal lab. The aim of the project is evaluating the performance of energy transfer based on the various leaves densities on the green facade. Heat calculation was used to calculate heat transfer on the wall surface. There are two kinds of leaves densities, 50% and 90%. The data measurement show that the green facade has a significant cooling effect and more visible for the facade with higher leaves densities. Respectively, from experiment I to experiment III, the average of heat fluxes are 22.35 W/m2, 8.76 W/m2, and 0.60 W/m2 where in experiment III, the negative heat flux occurred during day time due to interior surface temperature is higher than exterior surface temperature. Lastly, higher leaves densities possibility can create a better cooling effect but also has the risk of creating higher relative humidity, especially for the interior air layer.

Thermodynamics Performance Analysis of Solar Stirling Engines

This paper provides numerical simulation and thermodynamic analysis of SOLO 161 Solar Stirling engine. Some imperfect working conditions, pistons' dead volumes, and work losses are considered in the simulation process. Considering an imperfect regeneration, an isothermal model is developed to calculate heat transfer. Hot and cold pistons dead volumes are accounted in the work diagram calculations. Regenerator effectiveness, heater and cooler temperatures, working gas, phase difference, average engine pressure, and dead volumes are considered as effective parameters. By variations in the effective parameters, Stirling engine performance is estimated. Results of this study indicate that the increase in the heater and cooler temperature difference and the decrease in the dead volumes will lead to an increase in thermal efficiency. Moreover, net work has its maximum value when the angle between two pistons shaft equal to 90 degrees while efficiency is maximum in 110 degrees.

Research Note: A Method for Assessing the Maximum Temperature of Exhaust Valves in Internal Combustion Engines

The concept of mean cycle temperature has been used, by Seale and Taylor (1)§, to calculate heat transfer in pistons and liners of internal combustion engines. However, this technique cannot be used for exhaust valves because the valve temperature exceeds the gas mean cycle temperature. In this work it is shown that a ‘mean temperature’, based solely upon radiation considerations, yields a simple method for assessing the maximum temperature of exhaust valves and that the results obtained from engine tests are in close agreement with those predicted. The engine used in the investigation was a Mirrlees Blackstone K Major four-stroke diesel engine of 380 mm bore, operating with a b.m.e.p. of 1660 kN/m2at 600 rev/min.

Heat transfer through bark, and the resistance of trees to fire.

Measurements have been made of cambium temperatures in living trees subjected to mild and fierce fires. Fire resistance depends upon bark thickness: thus only big trees with thick bark can survive unharmed in really severe fires. The rate of change in cambium temperature is related to the thermal diffusivity of the bark, and is largely independent of bark structure or moisture content. A simple mathematical model is used to calculate heat transfer in bark, and the results obtained agree well with experimental measurements made on a variety of trees. Studies of soil temperature and results from experiments on pines are referred to briefly in appendices.