1. Heat and Power Technology Royal Institute of Technology, Stockholm 10044, Sweden e-mail:
2. Heat and Power Technology, Royal Institute of Technology, Stockholm 10044, Sweden e-mail:
3. Department of Mechanical Engineering, Duke University, Durham, NC 27708 e-mail:
4. Zucrow Laboratories, School of Mechanical Engineering, Purdue University, Purdue, IN 47907 e-mail: