The experimental and numerical research on microchannel heat transfer and fluid flow was presented in the paper. Diameters of the microtubes were 0.1, 0.3 and 0.5 mm and the flow regime was laminar with Re-number range up to 800. The working fluid was distilled water and the tube material was stainless steel. The experimental setup was designed in such a way that the investigation of the average friction factor and developing heat transfer was

In the present paper numerical modeling of a water flow through microtubes was made in order to analyze the behavior of the Poiseuille constant for the case of heating fluid flow inside the microtube. The microtube from the experimental research presented in [5] was used as a model. The length to diameter ratio of the tube was very large (L/Di = 1200), and a tube diameter was Di = 0.5 mm. Only a portion of the tube was heated with a Joule heating