Design of energy recovery systems: thermoelectric combi boiler generator and power analysis

Abstract

Gas-fired combi boilers are commonly used to meet the need for heating and general-purpose hot water indeveloping countries. In this study, a thermoelectric combi boiler generator (TECBG) was developed. When the boileris operated, cold water flows through the cold surface of TECBG and enters the boiler. In the same way, it is used byflows through the hot surface of TECBG in heated water. Thus, temperature difference occurrs between the surfacesof TECBG. The temperature difference is converted into electrical energy by Seebeck effect. The proposed system wasimplemented on a domestic combi boiler. The maximum temperature difference between the designed system and theTECBG surfaces was recorded as 48 ◦ C. 12V9AH battery was used to charge through a DC-DC charge regulator. About14.28 Wh power was generated by the TECBG when the temperature difference of the TECBG, current, and voltagewere 48 ◦ C, 1.18 A, and 13.8 V, respectively. The electrical energy consumed by the combi boiler was measured as115 Wh. Although the obtained energy is not quite high, it is an important gain in terms of energy efficiency becauseaccording to data recorded in Turkey, there are 15 million combi boiler users. Assuming that a single heating boilerruns for 4 h, it is possible to produce 306.6 GWh/year, derived from 14.28 Wh × 4 h × 365 days × 15,000,000 heatingboiler. The proposed system provides significant advantages and thus can decrease power consumption.