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In thermal engineering, the logarithmic mean temperature difference (LMTD) is used to determine the temperature driving force for heat transfer in flow systems, most notably in heat exchangers. The LMTD is a logarithmic average of the temperature difference between the hot and cold feeds at each end of the double pipe exchanger.
When stated in terms of temperature differences, Newton's law (with several further simplifying assumptions, such as a low Biot number and a temperature-independent heat capacity) results in a simple differential equation expressing temperature-difference as a function of time. The solution to that equation describes an exponential decrease of ...
The Food Safety (Temperature Control) Regulations 1995 Description English: These Regulations implement paragraphs 4 and 5 of Chapter IX of the Annex to Council Directive 93-43-EEC of 14th June 1993 on the hygiene of foodstuffs, as well as containing certain national provisions relating to food temperature control.
[11] [12] To prevent time-temperature abuse, the amount of time food spends in the danger zone must be minimized. [13] A logarithmic relationship exists between microbial cell death and temperature, that is, a small decrease of cooking temperature can result in considerable numbers of cells surviving the process. [14]
Time temperature indicators are commonly used on food, pharmaceutical, and medical products to indicate exposure to excessive temperature (and time at temperature). [1] In contrast, a temperature data logger measures and records the temperatures for a specified time period. The digital data can be downloaded and analyzed.
The first chapter describes the expected effects of climate change with one degree Celsius (1 °C) increase in average global temperature since pre-industrial times.. The second chapter describes the effects of two degrees average temperature and so forth until Chapter 6 which shows the expected effects of an increase of six Celsius degrees (6 °C) average global temperature.
These first Heisler–Gröber charts were based upon the first term of the exact Fourier series solution for an infinite plane wall: (,) = = [ + ], [1]where T i is the initial uniform temperature of the slab, T ∞ is the constant environmental temperature imposed at the boundary, x is the location in the plane wall, λ is the root of λ * tan λ = Bi, and α is thermal diffusivity.
Temperature sensitive products such as foods, [4] pharmaceuticals, [5] and some chemicals are often monitored during shipment and logistics operations. Exposure to temperatures outside of an acceptable range, for a critical time period, can degrade the product or shorten shelf life.