AbstractA portable solar conical concentrator of 1 metre aperture and consisting of 63 triangular plane mirror strips has been designed and fabricated. This device has been tested using cylindrical receivers having radii of 7.5 cm and 3 cm, respectively. It required 2 h for 8 kg of water in a large cylinder to reach boiling point, whereas it required only 20 min for 1.25 kg of water to boil in a smaller cylinder. The steam formed can be utilized to sterilize medical instruments or for other purposes as desired. The paper includes a detailed analytical treatment of heat exchange at the surface of the absorber, an evaluation of the appropriate heat transfer coefficients, and solutions of the energy balance equation for cylindrical absorbers of the sizes noted. Efficiencies as high as 60 per cent have been observed.