An instrument-based integrated architecture for developing a direct liquid-feed fuel cell system

Abstract

The design and control of the balance of plant (BOP) are vitally important for a self-sustainable and optimized fuel cell system. Since a variety of actuators and sensors should be integrated with the fuel cell stack to guarantee the system will sustain itself well, there should be control strategies regarding to the issues of fuel control, water management, heat management, safety, system diagnosis, optimization objectives, etc. It is therefore essential to construct an instrument-based integrated architecture to help the development of a fuel cell system, on which both the hardware components and the controlling algorithms can be evaluated, modified, and validated.

Accordingly, the present paper proposes an instrument-based DMFC system integrated by Matlab programs for the purposes of instrument control and data acquisition. It is achieved that 1) the fuel cell performance under various operating conditions can be evaluated automatically for a long period of time; 2) the controlling algorithms, such as sensor-less concentration estimation, fuel-in policies, efficiency optimization, state-of-charge estimation, safety considerations, flooding diagnosis, etc., can be evaluated and modified on the present platform; 3) the platform can also help to validate whether an actuator or a sensor is suitable for the designed fuel cell system.

A Brief Description

An instrument-based integrated DMFC system is shown in Fig. 1. All the instrument and components are integrated by Matlab 2008a on a PC server. The Instrument Control Toolbox in Matlab is adopted to construct the communication framework of the whole system. The Graphical User Interface Design Environment (GUIDE) is also introduced to acquire user-assigned conditions and to display the relevant information of the tested system.

The system mainly consists of a fuel cell stack with temperature module, as is shown in Fig. 2. An electric-load (Chroma 63030) and a micro-resistance meter (HIOKI 3561) are used for the testing and diagnosis. A mass-flow controller (Bürkert DS8712) is adopted for controlling the air stream. A density meter (Anton Paar DMA4100) and an electric scale (A&D GX-600) are employed to evaluate the status of the fuel. Besides, two diaphragm pumps (KNF nf5rtdc-m) are for the fuel circulation, which is controlled via a digital and analog I/O module. In addition, two micro-dosing pumps (Bürkert DS7616) are used for supplying water and neat methanol to regulate the quantity and concentration of the fuel in the mixing reservoir. Finally, temperature sensors, humidity sensors, as well as CO2 sensors, are embedded in the system. All the aforementioned instrument and components are communicated with and controlled by the PC server via GPIB, RS-232, RS-232c, and USB interfaces to construct the whole instrument-based integrated architecture.

Fig. 1. The instrument-based integrated DMFC system in TSINT.

Fig. 2. An illustrative diagram of the instrument-based integrated DMFC system in TSINT.