Experimental Investigation of Heat Loss from a Passive DMFC using Differential Interferometer

Abstract

The knowledge of heat loss from the fuel cell will be helpful to decide on material components and fixture design. In the present study, a new methodology is proposed to estimate heat loss from passive DMFC using interferometry technique. Printed circuit board (PCB) fixture is adapted in our study that replaces end plate and current collector. The accurate cell temperature distribution is useful to estimate the heat from the cell fixture. The cell temperature distribution is measured based on infra‐red (IR) thermography and this temperature distribution is used to estimate the heat transfer coefficient of the fuel cell. Differential interferometer (DI) technique is used to estimate the heat transfer under different operating conditions of the fuel cell. The cell surface temperature measured on the cathode gas diffusion layer (GDL) is 42 °C for 5M methanol concentration whereas for 1M, it is 32 °C. Based on the analysis , the average heat transfer coefficient of the cell at vertical PCB rib orientation using 5M methanol concentration is estimated to be 2.7 Wm−2 K−1. A two‐dimensional non‐isothermal single‐phase half‐cell (cathode) model is developed and compared with experiments. The cell temperature distribution obtained from model is in good agreement with experiments. The model is extended to study the effect of PCB orientation and thermal conductivity of PCB material on heat loss. The cell at vertical PCB rib orientation retains 15 ‐ 20% more heat than horizontal rib. Therefore, the cell temperature showed 42 °C and performed 10% better compared to horizontal PCB rib.

Investigation of In Situ Thermal Behavior of a Passive Direct Methanol Fuel cell Using Infra‐Red Thermography

“…The cell temperature due to exothermic reaction increases as both oxygen reduction reaction and methanol oxidation occur at cathode resulting mixed potential. In this connection, the cell performance is better due to increase in cell temperature that enhances chemical kinetics though the useful methanol crossover to cathode .…”

“…The thermal mass of the single cell is calculated to be 0.075 kJ K −1 , i.e., adding all “ mc p ” ( m – mass of the component, kg; c p – heat capacity of the component, kJ kg −1 K −1 ) fuel cell components except MEA. To ensure that the mass transport of reactants is influenced only by natural convection and prevent external flow disturbances, the entire cell assembly is kept in a wooden enclosure with glass window . In the case of active DMFC, a cartridge similar to anode side is attached on cathode PCB for air flow.…”

“…Based on the comparison of two temperature readings a calibration curve was plotted. The uncertainty of the measured temperature by IR camera ranges from –2.5% to +1.90%, which is almost close to the thermocouple readings .…”

Semiempirical thermodynamic modeling of a direct methanol fuel cell system

“…In passive systems, a methanol‐water solution is delivered to cells with less control over methanol through diffusion owing to a methanol concentration gradient and without the use of pumps. In addition, air flows into the cell by natural convection . These systems, which have been developed by some Japanese and Korean companies, can be used for low‐power applications such as personal digital assistant (PDA) devices and mobile phones.…”

“…In addition, air flows into the cell by natural convection. 7 These systems, which have been developed by some Japanese and Korean companies, can be used for low-power applications such as personal digital assistant (PDA) devices and mobile phones. In an active system, a fuel delivery system provides flexibility in system control as the mass flow rate of methanol and air, and the concentration of methanol can be controlled.…”