Electric heating is the process of converting electrical energy into thermal energy. Since the discovery that the power supply can cause thermal effects through wires, many inventors in the world have been engaged in the research and manufacture of various electric heating appliances. The development and popularization of electric heating is also the same as in other industries, following such a rule: gradually expanding from advanced countries to countries around the world; gradually developing from cities to rural areas; from collective use to households, to individuals; products from low-grade development To high-end. The electric heating appliances in the nascent stage of the nineteenth century were mostly poor. The earliest appeared electric heating appliances for life. In 1893, the prototype of electric comforter appeared and used in the United States, and then the use of electric stoves appeared in 1909. An electric heater is placed in the stove, that is to say, the heating is transferred from firewood to electricity, that is, from electrical energy to thermal energy. However, the rapid development of the real electric heating appliance industry came after the invention of the nickel-chromium alloy used as an electric heating element. In 1910, the United States successfully developed an electric iron made of nickel-chromium alloy electric heating wire, which fundamentally improved the structure of the electric iron, and the use of the iron quickly gained popularity. By 1925, products that installed electric heating elements in pots appeared in Japan and became the prototype of modern electric rice cookers. At this stage of industry, electric heating products such as laboratory electric furnaces, glue melting furnaces, and heaters also appeared. From 1910 to 1925, it was a big development stage in the history of electric heating appliances. In the household and industry, the emergence and popularization of various varieties of electric heating appliances have developed rapidly, especially in the household. Therefore, the invention of nickel-chromium alloys laid the foundation for the development of the electric heating appliance industry.
After the 1920s, there was not much new application development in the previous period, but during this period, all kinds of electric heating appliances have been re-ordered and continuously improved, becoming an improvement stage in the history of electric heating appliances. In household electric appliances, various appliances are designed to be more beautiful, durable and sturdy, and most of them have automatic temperature and time control.
unit of measurement
⒈Power: W, Kw 1Kw = 3.412BTU / hr British thermal unit / hour = 1.36 (horsepower) = 864Kcal / hr
⒉Weight: kg 1Kg = 2.204621b (pounds)
⒊Flow rate: m / min
⒋Flow: m3 / min, kg / h
⒌Specific heat: Kcal / (kg ℃) 1Kcal / (Kg ℃) = 1BTU / hr. ° F = 4186.8J / (Kg ℃)
⒍Power density: W / cm2 1W / cm2 = 6.4516 W / in2
⒎ Pressure: Mpa
⒏ Thermal conductivity: W / (m ℃) 1 W / (m ℃) = 0.01J / (cm s ℃) = 0.578Btu / (ft.hF)
⒐Temperature: ℃ 1F = 9/5 ℃ + 32 1R = 9/5 ℃ + 491.67 1K = 1 ℃ + 273.15