Numerical modeling of an automotive derivative polymer electrolyte membrane fuel cell cogeneration system with selective membranes

Abstract

Cogeneration power plants based on fuel cells are a promising technology to produce electric and thermal energy with reduced costs and environmental impact. The most mature fuel cell technology for this kind of applications are polymer electrolyte membrane fuel cells, which require high-purity hydrogen. The most common and least expensive way to produce hydrogen within today's energy infrastructure is through steam reforming of natural gas. Such a process produces a syngas rich in hydrogen that has to be purified to be properly used in low temperature fuel cells. However, the hydrogen production and purification processes strongly affect the performance, the cost, and the complexity of the whole energy system. Purification is usually performed through pressure swing adsorption, which is a semi-batch process that increases the plant complexity and incorporates a substantial efficiency penalty. A promising alternative option for hydrogen purification is the use of selective metal membranes that can be integrated in the reactors of the fuel processing plant. Such a membrane separation may improve the thermo-chemical performance of the energy system, while reducing the power plant complexity, and potentially its cost. Herein, we perform a technical analysis, through thermo-chemical models, to evaluate the integration of Pd-based H 2-selective membranes in different sections of the fuel processing plant: (i) steam reforming reactor, (ii) water gas shift reactor, (iii) at the outlet of the fuel processor as a separator device. The results show that a drastic fuel processing plant simplification is achievable by integrating the Pd-membranes in the water gas shift and reforming reactors. Moreover, the natural gas reforming membrane reactor yields significant efficiency improvements.

Comparison of integrated fuel processing options for biogas-fed solid-oxide fuel cell plants

“…Leveraging from the process simulation, we determine the optimal heat integration scheme of the plant with a MILP-based approach [11,12]. Therefore, the heat exchangers in the process simulation are represented by separate heaters and coolers to identify the heat and cold demand.…”

Combined heat, cooling, and power systems based on half effect absorption chillers and polymer electrolyte membrane fuel cells

“…We first study the performance of the power plant components through thermo-chemical models. Specifically, we further refine a previously studied and validated model [36,[53][54][55] for the CHP plant, enhancing thermal integration for both heat of process and cogeneration. In addition, we develop a thermo-chemical model for the half-effect absorption chiller, following a validated methodology [52,77].…”

“…The aim of this paper is to assess the environmental and economic impact of the integration of a half-effect absorption chiller in a PEMFC based CHP plant. We study the low temperature PEMFC CHP system, represented in Figure 1, that is connected directly to the Natural Gas (NG) line through a fuel processor [53][54][55]. A CHP system based on the same prime mover was already studied in [36,53] for different energy demands.…”

“…We perform the steady-state characterization of the PEMFC based CHP system with a thermo-chemical model, developed following a lumped parameter approach within the AspenPlus R [70] modeling environment. The thermal integration of the components have been refined [54,55] with respect to the prototype studied in [53]. Specifically the heat exchanger surface area is increased such that the pinch point temperature difference in all elements is set to 10 • C, to increase the fuel processor efficiency.…”

Pd-Based Membranes: Overview and Perspectives

“…For example, a 40 Nm 3 /h-class membrane reformer (MRF) system for H 2 production has been developed by Tokyo Gas, and its long-term durability and reliability have been demonstrated over 8000 h [ 18 , 19 ]. Along the same lines, Pd-based membrane integration is investigated in the fuel processor of distributed combined heating and power (CHP) plants employing fuel cell technology [ 20 ], leading to a drastic fuel processing plant simplification.…”