This paper is published as Open Access by Elsevier under the CC BY 4.0 licence.Waste heat recovery using a thermoelectric generator (TEG) is a promising approach for vehicle original equipment manufacturers to reduce fuel consumption and lower CO2 emissions. A TEG can convert otherwise wasted thermal energy from engines to electricity directly for use in the vehicle systems. This paper focuses on the development of a dynamic model of TEG system designed for vehicle waste heat recovery, which is made up of counter-flow heat exchangers (HXRs) and commercial thermoelectric modules (TEMs). The model is built from thermoelectric materials into a TEM and then into a TEG system. Compared to other TEG models, the tuning and validation process of the proposed model is more complete. Experiments are done on both a TEM test rig and a heavy-duty diesel engine, which is equipped with a prototype TEG on the exhaust gas recirculation (EGR) path. Simulations of steady-state operating points as well as the response to typical engine cycle test show good agreement with experimental data.\ud \ud A TEG installed upstream of the after-treatment system in a heavy-duty truck has been modelled to predict the temperatures and power output in a dynamic driving cycle. The simulation results of temperatures show the model can be used as a basis to develop a control system for dynamic operation to ensure safety operation of TEG and efficient operation of the after-treatment system. A comparison of power output of the systems under different scenarios underlines the importance of integration of TEM with HXRs. Based on the simulation results, around 20% average power output increase can be expected by optimizing the thermal contact conductance and the heat transfer coefficient of hot side HXR

The focus of the current study is on a state-of-the-art twin-layer gas diffusion layer (GDL) which\ud consists of carbon tissues with a fibre diameter of 5~20 μm, and contains a microporous layer (MPL)\ud coating which has sub-micron porous features. In the current study, real-world digital threedimensional\ud images of the GDL-MPL assembly are created through X-ray nano-tomography with a\ud 680 nm pixel resolution for the GDL and focused ion beam/scanning electron microscopy (FIB/SEM)\ud nano-tomography with a 14 nm pixel resolution for the MPL. The critical nano-structural features\ud including porosity, characteristics lengths and 3D pore size distribution are determined directly from\ud the 3D digital representation. In addition to morphological parameters, the FIB/SEM nanotomography\ud technique has been combined with lattice Boltzmann (LB) numerical modelling in order to calculate\ud the tortuosity and permeability of the MPL

This paper is closed access until 25th July 2018.A combined cooling heating and power (CCHP) system based on high-temperature proton exchange membrane fuel cell (PEMFC) is proposed. This CCHP system consists of a PEMFC subsystem, an organic Rankine cycle (ORC) subsystem and a vapor compression cycle (VCC) subsystem. The electric power of the CCHP system is 8 kW under normal operating conditions, the domestic hot water power is approximately 18 kW, and the cooling and heating capacities are 12.5 kW and 20 kW, respectively. Energy and exergy performance of the CCHP system are thoroughly analyzed for six organic working fluids using Matlab coupled with REFPROP. R601 is chosen as the working fluid for ORC subsystem based on energy and exergy analysis. The results show that the average coefficient of performance (COP) of the CCHP system is 1.19 in summer and 1.42 in winter, and the average exergy efficiencies are 46% and 47% under normal operating conditions. It can also be concluded that both the current density and operating temperature have significant effects on the energy performance of the CCHP system, while only the current density affects the exergy performance noticeably. The ambient temperature can affect both the energy and exergy performance of the CCHP system. This system has the advantages of high facility availability, high efficiency, high stability, low noise and low emission; it has a good prospect for residential applications

This paper is in closed access until 7th Jan 2017.A two-dimensional along-the-channel CFD (computational fluid dynamic) model, coupled with a two-phase flow model of liquid water and gas transport for a PEM (proton exchange membrane) fuel cell is described. The model considers non-isothermal operation and thus the non-uniform temperature distribution in the cell structure. Water phase-transfer between the vapour, liquid water and dissolved phase is modelled with the combinational transport mechanism through the membrane. Liquid water saturation is simulated inside the electrodes and channels at both the anode and cathode sides. Three types of models are compared for the HOR (hydrogen oxidation reaction) and ORR (oxygen reduction reaction) in catalyst layers, including Butler–Volmer (B–V), liquid water saturation corrected B–V and agglomerate mechanisms. Temperature changes in MEA (membrane electrode assembly) and channels due to electrochemical reaction, ohmic resistance and water phase-transfer are analysed as a function of current density. Nonlinear relations of liquid water saturations with respect to current densities at both the anode and cathode are regressed. At low and high current densities, liquid water saturation at the anode linearly increases as a consequence of the linear increase of liquid water saturation at the cathode. In contrast, exponential relation is found to be more accurate at medium current densities