Edge Cooling of a Fuel Cell during Aerial Missions by Ambient Air

Abstract

During aerial missions of fuel-cell (FC) powered drones, the option of FC edge cooling may improve FC performance and durability. Here we describe an edge cooling approach for fixed-wing FC-powered drones by removing FC heat using the ambient air during flight. A set of experiments in a wind tunnel and numerical simulations were performed to examine the efficiency of FC edge cooling at various flight altitudes and cruise speeds. The experiments were used to validate the numerical model and prove the feasibility of the proposed method. The first simulation duplicated the geometry of the experimental setup and boundary conditions. The calculated temperatures of the stack were in good agreement with those of the experiments (within ±2 °C error). After validation, numerical models of a drone’s fuselage in ambient air with different radiator locations and at different flight speeds (10–30 m/s) and altitudes (up to 5 km) were examined. It was concluded that onboard FC edge cooling by ambient air may be applicable for velocities higher than 10 m/s. Despite the low pressure, density, and Cp of air at high altitudes, heat removal is significantly increased with altitude at all power and velocity conditions due to lower air temperature.

Simulation Approaches and Validation Issues for Open-Cathode Fuel Cell Systems in Manned and Unmanned Aerial Vehicles

“…In [17], heat spreaders and/or heat pipes have been proposed for a medium-scale (<10 kW) fuel cell. Such solutions increase the volume of the stack and require a higher flow of air than conventional air-cooling solutions but can be effective for UAVs [18]. A high-temperature air-cooled PEMFC is used in the Zeroavia project [11].…”

“…In aerial applications, the very dry and cold ambient air, together with the presence of dust, can harm the membrane of the fuel cell. In [18], a dome with regulated ventilation is proposed to solve this problem as well as to allow the retrieval of the water vapor generated by the fuel cell.…”

“…Saadi et al [26] used electrochemical impendence spectroscopy (EIS) to investigate the phenomena of diffusion and charge transfer. Wind tunnels are employed in [18] to study edge cooling in a UAV and in [75] to measure the convective heat transfer coefficient of a PEM. In [30], the stack is tested in an environmental chamber that allows the control of humidity, temperature, and oxygen concentration.…”

A Review on Key Technologies and Developments of Hydrogen Fuel Cell Multi-rotor Drones

“…This is particularly advantageous in low-power devices, such as drones, which require less heat dissipation. Depending on their structure, air-cooled PEMFCs can be further subdivided into three types: area air-cooled [27], edge air-cooled [28,29], and open-cathode type [30]. In the open-cathode type, the cathode channel is exposed to the atmosphere, and the flowing air simultaneously provides the oxygen required for the cathode reaction and cools the stack through fan suction.…”

Semi-Empirical Models for Stack and Balance of Plant in Closed-Cathode Fuel Cell Systems for Aviation

“…Edgecooling makes use of fins on the stack and can improve the maximum stack power by more than 15% [13]. This increases the volume of the stack and requires a high flow of air but can be effective for UAVs where the ambient flow can be utilized for heat removal [28].…”