Heat generator and design method thereof

A heat generator comprising a working chamber defined in a housing, a viscous fluid accommodated in the working chamber, and a rotor rotationally driven by an external power,

• wherein the working chamber includes a heating generating area for accommodating the rotor in such a manner as to secure a fluid-tight gap between a partitioning wall and the rotor and for generating heat by shearing the viscous fluid existing in the fluid-tight gap by the rotor, a storage area for accommodating the viscous fluid exceeding the volume of the fluid-tight gap, and at least one opening formed in the boundary between the heat generating area and the storage area for communicating the two areas,
• wherein the working chamber includes supply means for transferring the viscous fluid in the storage area to the heat generating area at the time of rotation of the rotor and recovery means for transferring the viscous fluid in the heat generating area to the storage area at the time of rotation of the rotor,
• wherein the recovery means includes at least a recovery groove formed in the partitioning wall of the working chamber in opposed relation to the shearing surface of the rotor for trapping the viscous fluid existing in the fluid-tight gap and forcibly transferring it toward the opening at the time of rotation of the rotor, and
• wherein said supply means and said recovery means are so constructed that the outflow ratio (α), i.e. the ratio of the amount of the viscous fluid flowing out of the heat generating area due to the forcible transfer operation of the recovery groove to the total amount of the viscous fluid flowing into the heat generating area from the storage area due to the transfer function of the supply means, is not more than 0.92.