Ilios Dynamics, a subsidiary of Waltham-based energy systems company Tecogen Inc., said Thursday that it sold seven of its natural gas engine-driven heat pumps to a biomedical research facility in Florida. Ilios Dynamics, a subsidiary of Waltham-based energy systems company Tecogen Inc. , said Thursday that it sold seven of its natural gas engine-driven heat pumps to a biomedical research facility in Florida.