What is it about?
This paper introduces a clever, non-touch way to measure temperature in heat pumps that use a harsh chemical mix of lithium bromide (LiBr) and water—common in eco-friendly cooling systems powered by solar or waste heat. Traditional sensors corrode quickly because LiBr is superoxidizing, so the team tested shining light through the solution and measuring how much gets through (transmittance) at specific infrared wavelengths (1.33 and 1.55 microns). They experimented with solutions at 49-60% LiBr strength and temperatures from 25-80°C, finding clear patterns: at 1.55 microns, transmittance drops linearly with rising temp, making it easy to calculate; at 1.33 microns, it's a curve. This optical trick avoids direct contact, letting you monitor the system's guts safely and instantly. It's like using a laser pointer to "feel" the heat without getting burned. Could make heat pumps more reliable for air conditioning, water purifying, or heating in dry areas, saving energy and cutting maintenance hassles while boosting green tech.
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Why is it important?
This technique innovates by enabling contact-free, real-time temperature sensing in corrosive LiBr systems via optical transmittance—sidestepping electrode degradation in traditional methods. Timely for advancing sustainable energy amid climate pushes, it could enhance heat pump efficiency by 10-20% through better control, aiding solar refrigeration in water-scarce regions, and reducing operational costs/downtime for broader adoption in renewables.
Perspectives
Experimentally, the study characterizes LiBr-H2O (49-60 wt%) transmittance spectra (1-4 µm) at 25-80°C, identifying optimal windows at 1.33 µm (parabolic T-I correlation, R²>0.99) and 1.55 µm (linear T-I, slopes -3937 to -1232 °C/unit-I); static quartz cell setup with spectrum analyzer validates for absorber/generator monitoring in absorption heat pumps, assuming steady-state, with potential for dynamic flow integration.
Professor Rosenberg J Romero
Universidad Autonoma del Estado de Morelos
Read the Original
This page is a summary of: Temperature sensing based on optical transmission in a LiBr heat pump, MRS Proceedings, January 2005, Springer Science + Business Media,
DOI: 10.1557/proc-0888-v03-17.
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