Javed, AdeelArpagaus, CordinBertsch, StefanSchiffmann, Jürg2016-08-242016-08-242016-08-24201610.1016/j.ijrefrig.2016.06.015https://infoscience.epfl.ch/handle/20.500.14299/128843WOS:000381838200025Two mechanically driven small-scale turbocompressors running on gas lubricated bear-ings have been theoretically designed for a 6.5 kW two-stage heat pump functioning under variable operating conditions. The novelty in the heat pump system lies in the application of oil-free turbocompressor technology and the introduction of unused heat from various secondary heat sources. Managing the heat pump operational deviations with the second-ary heat is difficult for the turbocompressors. The turbocompressors can potentially exceed their operating range defined by the surge, choke and maximum rotational speed margins. Furthermore, regulating the tip-leakage flow caused by large tip-clearances in small-scale turbomachinery is challenging. This paper will guide the readers through different stages of the design process of small-scale turbocompressors subjected to different operational and design constraints. The design review and the presented methodology will help the de-signers make suitable parameter selections for achieving high efficiency and wide compressor operating range.Two-stage heat pumpSmall-scale turbocompressorsTwo-zone meanline modelingTip-clearance effectsOptimum blade designComputational fluid dynamics (CFD)text::journal::journal article::research article