Patent ID: 6445880
Filing Date: 2002-09-03
Classification: F24H,G05D

Abstract:
A heating system for supplying a liquid at a predetermined setpoint temperature, comprising:a heat exchanger tank having an inlet for receiving an inlet flow of liquid into the tank, an outlet for allowing an outlet flow of liquid to leave the tank; a heater positioned in the heat exchanger tank and configured to heat the liquid passing through the heat exchanger tank from the inlet to the outlet; an inlet flow diverting pipe carrying a portion of the inlet flow diverted from flowing into the heat exchanger tank; an outlet flow diverting pipe carrying a portion of the outlet flow diverted from the outlet; a mixed flow pipe configured to carry a mixed flow of liquid partially received from the inlet flow diverting pipe and partially received from the outlet flow diverting pipe; a first tuning valve on the inlet flow diverting pipe to control flow in the inlet diverting pipe and a second tuning valve on the outlet flow diverting pipe to control flow in the outlet diverting pipe, wherein the tuning of the first tuning valve and the second tuning valve provides a fixed ratio of inlet flow and outlet flow into the mixed flow pipe; a temperature sensor configured to determine the temperature of the mixed flow in the mixed flow pipe; and a temperature control system configured to modulate the current to the heater in response to the temperature of the mixed flow in the mixed flow pipe based on a monotonic, empirical relationship between the temperature of the mixed flow in the mixed flow pipe and the current applied to the heater determined by the setpoint temperature and the tuning of the first tuning valve and the second tuning valve.