Analysis of temperature characteristics of lighting

The temperature of the lamp bulb (including the internal gas temperature) affects the temperature of the cold end of the lamp, that is, the temperature of the amalgam placed on the cold end affects the mercury vapor pressure of the lamp, thereby affecting the light efficiency. In order to analyze the temperature characteristics of the lighting bulb and study the influence of the temperature of the bulb on the temperature of the cold end, we use the ThermaCAM PM525E infrared thermal imager from FLIR in the United States. The thermal infrared imager uses an infrared detector and an optical imaging objective lens. The infrared radiation energy distribution pattern of the received target is reflected on the photosensitive element of the infrared detector to obtain an infrared thermal image, which corresponds to the thermal distribution field on the surface of the object. In layman's terms, an infrared thermal imaging camera converts the invisible infrared energy emitted by an object into a visible thermal image. The different colors on the top of the thermal image represent different temperatures of the measured object. The temperature of the bulb of the 150W phosphor-coated and non-phosphor-coated lamps was measured (measurement conditions: distance 2m, ambient temperature 21°C), and the results are shown in Figure 3. From Figure 3(a), it can be seen that after lighting, the temperature of the fluorescent powder lighting first increases rapidly, reaching about 70°C in 1 minute, and reaching the first peak (about 112°C) in about 7 minutes, and then the temperature drops slightly, and then Continue to rise. The lamp is on for about 20 minutes and reaches the maximum value of 116°C in the experimental range. Similarly, from Figure 3 (b), it can be seen that after lighting, the temperature of the phosphor-free lighting first increases rapidly, reaching about 70°C in 1 minute, and reaching the first peak (about 124°C) in about 7 minutes, and then the temperature drops slightly, and then It continued to rise again, reaching the maximum value of 135°C within the experimental range in about 20 minutes. Comparing the temperature rise characteristics of lighting with and without phosphors, it can be seen that they have temperature rise curves of similar shape, but the temperature rise amplitude is different. The reason for this phenomenon is: after the lighting is lit, the electrons in the bulb are generated in the coupler Under the action of the high-frequency electromagnetic field, the gas atoms in the lamp are impacted to generate plasma. The plasma interacts with the inner wall of the glass bulb (or phosphor layer, etc.) to generate a lot of heat. In addition, ferrite cores and coils also generate a lot of heat. This heat causes the temperature of the lamp bulb to rise. When the lamp is on for about 7 minutes, the metal base starts to dissipate heat, which reduces the temperature. When the heat gained by the base is balanced with the heat dissipated, the temperature no longer drops. The discharge in the bulb and the heat generated by the coupler continue to increase, so that the heat generated by the discharge is greater than the heat dissipated by the base, and the temperature of the bulb continues to rise. For the case where the body temperature rise of the lamp with and without the phosphor is quite different, the conversion form of the formula of the specific heat capacity of the substance can be Qu003dcmΔt (Q is the heat, c is the specific heat capacity of the substance, m is the mass of the substance, Δt is The amount of temperature change) to analyze. It can be seen from the above formula that when the discharge produces the same amount of heat, due to the presence of phosphors, the system with phosphors contains more substances than the system without phosphors, and the phosphors will also absorb heat from the system to increase its own temperature, so When there is phosphor, the temperature rise of the system is lower than the system without phosphor because the phosphor absorbs part of the heat. Regarding the temperature characteristics after turning off the lights, by comparing the temperature curves after the lights are turned off in Figure 3(a) and Figure 3(b), it is found that the temperature curves of the two are very close. This shows that the heat dissipation effect of the metal base of the lighting is basically the same. In order to better analyze the temperature of these two kinds of lighting, the temperature distribution photos of the bubble body during heating and cooling are obtained with an infrared thermal imaging camera, as shown in Figure 4 and Figure 5, respectively. It can be seen from Fig. 4 (a) that the highest temperature of the lamp with phosphor is 104°C 10 minutes after it is lit, and the temperature at the main amalgam has exceeded 45.3°C, that is to say, the light of the lamp starts at this time. The efficiency has dropped because the mercury pressure corresponding to the best light efficiency is about 7mtorr, and the corresponding cold junction temperature is about 42°C. At this time, the maximum temperature of the phosphor-free lighting is 122°C, and the cold end temperature of the amalgam is still lower than 45.3°C (see Figure 4(b)). Figure 4 and Figure 5 are photos of the thermal imaging camera 4 minutes after the lights are off. Comparing the fluorescent powder and non-fluorescent powder lamps, the maximum temperature of the two is basically the same (68℃ and 67℃), but the temperature distribution is slightly different. This is because the maximum temperature of fluorescent powder lamps is higher than that of fluorescent powder lamps. The maximum temperature is high. At the same time, it can be seen that the cooling rate of the bulb is very fast, while the cooling of the base is very slow. With the change of the light-off time, the highest temperature of the bulb is transferred from the bulb to the base, so mercury vapor may be adsorbed on the inner wall of the bulb. Above, this is very unfavorable for designing a dynamic pumping and aspirating experimental system. Figure 5 In summary, the temperature change of the bulb body of the lamp has a great influence on the temperature of the cold end of the bulb. In order to make the temperature of the amalgam placed at the cold end of the bulb in the best state, it is necessary to design a bulb with a very reasonable structure and shape and heat dissipation. 4 Conclusion The lighting is a kind of electromagnetic induction lamp. The induction lamp is designed with imported technology MCU circuit. The active infrared working mode has the characteristics of good stability and strong anti-interference. It has an infrared decoding method and is widely used in more demanding applications. High commercial and industrial occasions. It is a new generation of green energy-saving lighting fixtures. Its luminous efficiency has an important relationship with the temperature of the amalgam placed at the cold end of the bulb. Analyzing the temperature characteristics of the bulb plays an important role in designing a reasonable heat dissipation structure for lighting and improving the energy-saving effect of the lamp. The heating and cooling characteristics of the lamps with and without phosphors are measured with an infrared thermal imaging camera. It is found that the shape of the temperature rise and fall curves of the two are basically the same, but the temperature rise amplitude is different. The reason is The heat absorption of the phosphor increases its own temperature. In addition, it can be seen from the image of the thermal imager when the temperature is raised that the light efficiency of the lamp drops after 10 minutes of lighting. Therefore, to improve the luminous efficiency of lighting, it is very important to design a reasonable bulb and radiator structure and shape.