Absolute temperature or thermodynamic temperature, is the temperature of a gas or substance on a scale, in which the least possible temperature is the absolute zero. At the lowest point, the kinetic energy of the molecules, responsible for work and heating, is equal to zero. This means that absolute temperature measures the lowest thermal energy state of a substance.
The absolute temperature is considered the proper temperature scale, for substances that function at lower temperatures. In the cold chain industry, the absolute temperature is used to determine the level of coldness achieved, as against the absolute zero. The internationally recognized scale for measuring absolute temperature is the Kelvin scale (K). The absolute zero in the Kelvin scale is pegged at 0k.
Applications for Absolute Temperature
Absolute or thermodynamic temperature is very useful in many ways. It is used to measure and compare the temperature of a substance, to absolute zero. This determines how truly cold the substance is. Its application in the cold chain industry helps to improve refrigeration – making preservation of substances better.
Gas Laws and Applications
Absolute temperature is very useful in many disciplines and fields, involving the use of gases. Gas laws and equations which govern the behaviour of gases, are founded upon the absolute temperature. Using the absolute temperature, gases can be studied and utilized to solve problems in the real world.
In the cold chain industry, the properties of gases at absolute temperatures are used to determine which function better, when used as coolants. Absolute temperature is used in determining how temperature change affects the pressure of refrigerated van tyres. With the information, the tyre pressure limit is set, and the mileage covered by the vehicle, improved.
The Thermodynamic Temperature Scale
There are several temperature scales in use, like the Celsius scale, the Fahrenheit scale, and the Ranking scale. These scales have negative temperatures, representing extremely cold states. Unlike these, the thermodynamic temperature scale has 0K as its lowest point – the absolute zero. Temperatures beyond this point, are considered impossible to achieve. This makes the thermodynamic temperature scale, the best for temperature change comparisons.
The triple point of water is 273.15K. The boiling point of water is approximately 373K, which is equal to 100°C. Standard room temperature is pegged at 298.15K. For standard coolants used in the cold chain industry, dry ice sublimates at approximately 195K and Norflurane has a melting point of about 170k.
Absolute Temperature and Coldness
Absolute temperature is used to compare the temperature of substances to absolute zero – effectively measuring how truly cold the substances are. With the thermodynamic temperature scale, there is no truly negative temperature, as temperatures beyond 0K are yet to be realized.
At Glacier vehicles, our new freezer vans guarantee cold temperatures of up to -25°C. At this temperature, your meat, medicine, and perishable products are preserved effectively. Measured using the thermodynamic temperature scale, this equates to 248.15K.
How Cooling Works
In a standard cooling system, cooling is achieved by one-directional heat transfer from the substance, to the outer environment, using a coolant. The coolant is pumped around the environment to be cooled, by the engine. Using thermal engineering and proper thermal insulation, heat energy is picked up by the coolant, from the substance and transferred to the outer environment.
Achieving Temperature Control in Cold Chain Systems
The standard refrigeration temperature is approximately 274.6K. At this temperature, your perishable foods are barely kept from freezing (at 273.15K). For the cold chain systems, temperatures cooler than these, are sometimes needed. In order to achieve and maintain perishable foods at a suitable absolute temperature, better refrigeration units and proper thermal insulation, are required.
Refrigeration and Thermal Insulation
In order to maintain the right absolute temperature, heat transfer must be one-directional. This means heat is only required to flow from the refrigeration unit, to the outer vehicle. For this to be achieved in a cold chain system, the refrigeration unit must possess proper thermal insulation. Using knowledge of thermal engineering and material science, heat transfer in the opposite direction, is kept at the barest minimum.
Cooling Efficiency of Refrigerated Vehicles
To maintain a stable absolute temperature, new and used refrigerated vans must be thermally insulated. The vehicles also require powerful engines, to keep the refrigeration units functioning at their best.
At Glacier Vehicles, we have used and new refrigerated van models, from top manufacturers. These models such as the Ford Transit, Iveco Daily, Fiat Scudo, and Renault Master, are equipped with powerful engines. For thermal insulation, our vehicles make use of a four-part refrigeration process,
- The Styrofoam (polystyrene foam) – which has trapped air bubbles that prevent heat energy from flowing through it. It is 50-mil thick in fridge vans, and 75-mil thick in new and used freezer vans. The density of foam is also very instrumental, in the insulation process.
- The wood boarding – which adds extra resistance to the passage of heat. We treat the boarding with food-safe anti-bacterial fungicides, to prevent rot.
- The fibreglass-like interior sheeting – that acts as a keying agent, to the GRP resin.
- The GRP resin interior – finished with a wet lay roller, and providing a 100% hygienic, and cleanable loading area, when dry.
Better Cooling with Glacier Vehicles
For better cooling efficiency and your logistics needs, Glacier Vehicles refrigerated vans are right for you. At every point in time, we have more than 40 vehicles in our showrooms, ready to be delivered at your doorstep, on demand. We also offer bespoke fittings, which will meet your supply chain needs. Our trained engineers are always available, to assist in emergency cases.