Abstract
The heat exchanger in a gas instantaneous water heater is a thermal device used for heat transfer from the high-temperature flue gas to the low-temperature water. The fireside corrosion, due to the reaction of acidic condensate formed on the heat exchanger surfaces and its metallic material, is one of the major hazards for gas instantaneous water heaters. This paper focuses on identifying and quantifying the fireside corrosion on the surface of heat exchangers in gas-fired instantaneous water heaters. Durability tests lasting for 2000 cycles were undertaken for five gas-fired instantaneous water heaters, which were different in terms of the heat input and coating of heat exchangers. The corrosion deposits on the surface of the heat exchangers were surveyed by several methods. The results show that the corrosion deposit grew as the test duration increased. The fins of the heat exchanger with a lead coating had been corroded and copper was exposed. Cu4(OH)6SO4 was the main corrosion product of heat exchangers without a lead coating, whereas PbSO4 was the main corrosion product of heat exchangers with a lead coating. The experiments demonstrate that the corrosion rate decreased with the increase of the heat input. The experiments also show that the thermal efficiency of gas instantaneous water heaters decreased by 2.4% to 6% at the end of the test duration.
Highlights
The energy used for global building accounts for 35% of the total energy consumption [1]
In theHowever, current research, we aimed to identify and quantify the process of corrosion failure the characteristics of fireside corrosion during the actual operation remain unclear.in
Inthe the heat exchanger and assess its effect on the thermal performance of the gas-fired instantaneous water current research, we aimed to identify and quantify the process of corrosion failure in the heat exchanger heaters in its service
Summary
The energy used for global building accounts for 35% of the total energy consumption [1]. Similar to the global energy consumption, the amount of building energy expense in China was 857 million tons of standard coal, accounting for 20% of the country’s total energy expense, in 2015, according to the statistics of the China Association of Building Energy Efficiency [2]. It indicated that the energy usage of urban residential and rural buildings was 320 million tons and 197 million tons, respectively. The water water firstly firstly flows flows through through the the pipes pipes around around the the outside outside of of the combustion combustion chamber, chamber, and and enters enters the the heat heat exchanger exchanger pipes, pipes, where where itit obtains obtains heat heat from from the the flue flue gas gas in in the the combustion chamberand and exchanger by conduction, heat conduction, convection and After radiation.
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