Emissivity Measurement Apparatus
Product Code : EL-HTL-11088
Quick answer: The emissivity measurement apparatus finds the emissivity of a test surface by comparing it with a black plate of the same size. Both 160 mm aluminium plates have mica heaters and separate dimmers; when they are held at the same temperature, the difference in heater input comes from radiation alone. Lab Exports manufactures it in Delhi for engineering colleges, polytechnics and TVET institutes.
Specifications
| Component | Specification |
|---|---|
| Plates | Test plate and black plate, aluminium, 160 mm dia. |
| Heaters | Mica heater inside each plate |
| Heater control | Separate dimmers for each plate |
| Power measurement | Voltmeter and ammeter with selector switch |
| Temperature measurement | Multichannel digital indicator |
| Enclosure | Panel with Perspex front |
| Services | 230 V, 15 A AC supply with earthing; space 1.5 x 1 m at working height |
How the emissivity experiment is done
Emissivity, epsilon, is the ratio of the radiation a surface emits to that of a black body at the same temperature. A hot plate loses heat by convection and by radiation. If the test plate and the black plate are the same size, in the same enclosure and at the same temperature, their convection losses match, so any difference in electrical input must come from their different emissivities.
Taking the black plate as epsilon = 1, the input difference is Wb - Wt = (1 - epsilon) sigma A (Ts^4 - Ta^4), where Ts and Ta are the absolute plate and enclosure temperatures and sigma is the Stefan-Boltzmann constant. Solving for epsilon gives the emissivity of the test surface.
- Switch on both heaters and set their inputs with the dimmers.
- Adjust the dimmers until both plates reach the same steady temperature.
- Read the voltage and current for each plate using the selector switch.
- Note the plate and enclosure temperatures.
- Calculate epsilon, then repeat at a different temperature.
Key features
- Test plate and black plate of identical 160 mm aluminium construction
- Mica heater inside each plate
- Separate dimmers so both plates can be held at equal temperature
- Voltmeter and ammeter with selector switch for either heater
- Multichannel digital indicator for both plates
- Perspex-fronted panel shields the plates from draughts while keeping them in view
Documentation and supply
Installation instructions and a manual are supplied with the apparatus. Most Lab Exports products carry a one-year manufacturer warranty.
Lab Exports manufactures the emissivity apparatus at its works in Laxmi Nagar, Delhi, and supplies it to engineering colleges, polytechnics and TVET institutes in India and 60+ countries, handling the export documents for each shipment. More about the company is on the About Lab Exports page.
Related Heat Transfer Lab products
- Heat Transfer in Agitated Vessel (EL-HTL-11087)
- Stefan-Boltzmann Apparatus (EL-HTL-11089)
- Critical Heat Flux Apparatus (EL-HTL-11090)
- Specific Heat of Air Apparatus (EL-HTL-11085)
- Concentric Tube Heat Exchanger (EL-HTL-11091)
- Forced Convection Apparatus (EL-HTL-11084)
The full range is in the Heat Transfer Lab section of the Engineering Lab range.
Frequently asked questions
Why is a black plate used in the emissivity apparatus?
It acts as a reference. When both plates are the same size and temperature, convection losses are equal, so the difference in heater input is due to radiation and gives the emissivity of the test plate.
How are the two plates kept at the same temperature?
Each plate has its own dimmer, so its heater input can be adjusted independently until the temperatures match.
What is the price of the emissivity apparatus?
Prices are not published on the website. Add the emissivity apparatus to the Enquiry Cart with the Add To Cart button on this page, or email [email protected] with the house code EL-HTL-11088 and the quantity, to receive a quotation.
Does Lab Exports manufacture the emissivity apparatus?
Yes. Lab Exports manufactures the emissivity apparatus at its works at 11/315, Lalita Park, Laxmi Nagar, Delhi 110092, under house code EL-HTL-11088.
Request a quote
Email [email protected] with the house code EL-HTL-11088 and the quantity, or add the emissivity apparatus to the Enquiry Cart with the Add To Cart button on this page. Tender buyers can also see the Tenders and OEM page.