06/02263 Combustion simulation of turbocharger HSDI Diesel engines during transient operation using neural networks: Galindo, J. et al. Applied Thermal Engineering, 2005, 25, (5–6), 877–898.

• Publisher: Elsevier Science
• Year: 2006
• Weight: 331 KB
• Volume: 47
• Category: Article
• ISSN: 0140-6701
• DOI: 10.1016/s0140-6701(06)82271-x

✦ Synopsis

Trigeneration can be considered as a special case of the application of cogeneration systems where a fraction of the shaft work or residual heat is used for running a refrigeration system. This work focuses on trigeneration schemes where a gas turbine is used as a prime mover for power production and cooling is generated by a typical compressionrefrigeration system. In most applications, a gas turbine will meet either the process power requirements or the heating needs, but it is unlikely that both would be satisfied simultaneously in the most efficient manner. The selection of the gas turbine that minimizes the heat losses to the ambient while supplying the required power can be readily accomplished by superimposing the turbine exhaust gas temperature profile to the process streams profile in a T vs enthalpy curve. This is because the maximum overall efficiency depends on the process heat and power demands and on the shape of the heat demand profile of the process. The use of the thermodynamic model helps to simulate the main components of the system and permits a fast and interactive way to design the optimum trigeneration scheme using the performance data of commercial gas turbines.

Thermal performance of non air-conditioned buildings with vaulted roofs in comparison with flat roofs

Tang, R. et al. Building and Environment, 2006, 41, (3), 268 276. Vaulted or domed roofs have been frequently adopted by builders and architects throughout the Middle East and other hot dry areas. However, the thermal performance of such buildings under hot dry climatic conditions has rarely been quantitatively studied. In this paper, a detailed finite element model for the investigation of the thermal performance of non air-conditioned buildings with vaulted roofs (VR) is suggested based on two-dimensional unsteady heat transfer in such roofs and solar geometry. This model allows a comparison of the thermal performance of non air-conditioned buildings with a VR and a flat roof (FR) under different climatic conditions. Results obtained by numerical calculation show that, irrespective of building type the VRs are applied to, buildings with a VR have lower indoor temperatures as compared to those with a FR. The reason is that such roofs dissipate more heat than a FR does by convection and thermal radiation at night due to the enlarged curved surfaces. This implies that such roof forms are suitable for buildings located in hot dry regions but not for those located in hot humid areas, and reasonably explains why curved roofs have been extensively adopted by builders and architects in the hot dry areas in the past. However, with the decrease in the half rim angle of a VR, the difference of indoor thermal condition between a VR and a FR building becomes small and insignificant. Results also indicate that the indoor air temperature is slightly influenced by the half rim angle 00 and the orientation 0v of the VR. To be effective to create a favourable thermal condition inside buildings with a VR under hot dry climatic conditions, the half rim angle of a VR should be 00>50 °, instead of 0o<50 ' ~, which is the optimal half rim angle of a VR of air-conditioned buildings, as found by the present authors in a previous study.