When does the Classical Heat transfer fail / stop to work , i.e, when will the quantum effects have any effect on the heat transfer. My problem is a heat transfer between a Spherical Bacterial Spores(an agglomerate) and a hot gas (take Nitrogen) . I really dont know whether the spores can be considered as Solid with a lattice structure Also i want to know what is the role of Energy Accommodation Coefficient ? Because in classical heat transfer and our calculations we consider it as 1 , but recently came across in a paper that it maybe close to zero , does this affect the heat transfer ? I have attached two papers where they say the Enegy accomodation coefficient maybe around zero . Please help me out..