 SEATTLE, Sept. 3, 2021 PRNewswire -- ClearSign Technologies Corporation Nasdaq: CLIR ClearSign or the Company, an emerging leader in industrial combustion and sensing technologies that improve energy, operational efficiency and safety while dramatically reducing emissions, announces that it has received a verbal notification from ExxonMobil to put on hold the testing of its ClearSign CoreTM process burners to be installed at the Baytown, Texas refinery. 