To achieve climate neutrality in aviation by 2050, hydrogen powered aircraft propulsion can be key. For this, several challenges need to be tackled such as thermal management and heat rejection of fuel cells in the aircraft. For each watt of electricity produced by a fuel cell, one watt of waste heat is generated. Recuperating it to further use would be indeed an asset. The exFan project will target such innovation by including a ducted heat exchanger in the nacelle of the propulsion system. It will use the ram jet effect, called also "Meredith effect" (ME) to generate thrust from waste heat. The design of a lightweight heat exchanger and the recovery of waste heat using the ME are promising topics further investigated in detail here. The exFan system will be included in a geared electric fan propulsion system of mega-watt class powered by hydrogen fuel cell technology. The heat exchanger will be a bionic design duly surface finished to hinder particle accumulation, corrosion, and erosion. Additionally, novel thermal management system will be designed, to optimize the heat quality of the waste heat and control the heat flux of the propulsion system. Optimal operation conditions will also be investigated. A simulation model will be set up for operation parameter optimization. First functional lab scale tests of exFan will serve to verify such model. The breakthrough innovations proposed in exFan will i) allow European aircraft producers to offer savings in cost operation ii) enable European aeronautics industry to maintain global competitiveness and leadership, and iii) create significant contribution in the path towards CO2 and NOX emission free aircrafts. exFan brings together multidisciplinary experts from academia, aeronautical associations and industry, supported by a selected technical advisory board. exFan will be in close contact with Clean Aviation and Clean Hydrogen to create synergies and speed up the development.