Primary Study Of The Electrochemical Ammonia Compression Technology Based On The Fuel Cells

Ammonia is an excellent refrigerant which has many advantages,such as low cost,moderate pressure,large unite refrigerating capacity,high coefficient of heat release and small flow resistance.Ammonia is almost used in the food processing cooling equipment,such as cold storage,refrigerator,air-conditioning and so on.The ammonia compressor is the core component of air conditioning refrigeration cycle system.As the core technology of the compression,its research and innovation plays a decisive role.In this experiment,we proposed a technology of the ammonia compression and have a preliminary study.An atmospheric pressure mix gases of ammonia and hydrogen are used in the electrochemical compress process,we get a higher pressure mix gases of ammonia and hydrogen.The device is similar to proton exchange membrane fuel cells and the core structure is membrane electrode.The gas diffusion layer of the membrane electrode is the suppore body of the catalyst.Pt loading at anode and cathode is 0.4 mg/cm2,Nafion 117(N117)membrane is used and the N117 membrane is converted into NH4+ type.The ionic conductivity of the NH4+ type N117 membrane is measured by the AC impedance method,the result shows that the ionic conductivity of the NH4+ type N117 membrane is lower 3-4 times than the H+ type N117 membrane under the same humidity.The membrane electrode is assembled into a single cell.The single cell is applied into the electrochemical ammonia compression system,the humidified mix gases of ammonia and hydrogen enter the anode gas inlet.Ammonia is neutralized by the proton and generated the ammonium.So ammonia transported as ammonium,through a Nafion(DuPont)117 membrane from the inlet(anode)to the outlet(cathode)compartments of the cell under the external potential.At the cathode,the ammonium ions and the electrons will combine to regenerate the high pressure mix gases of ammonia and hydrogen.This study investigates the influence of the different ratio of the inlet gas at the anode,the relative humidity,the temperature and the applied voltage for the optimum electrochemical compression conditions.The active area of the membrane electrode is 2 cm × 2 cm,at the room temperature(25?),the pressure of the inlet gas is 100 kPa and the ratio of the ammonia and hydrogen is 2 to 1,a cell voltage of 0.6 V is required and then running 86 minutes,the pressure of the outlet gases can reach to 886 kPa.We use the gas chromatography to analysis the compositions of the outlet gases,the results show that the compositions are ammonia and hydrogen and the ratio is 2 to 1.