Cooling, not ‘cold supply’ – on the correct use of terminology

Is the term ‘cold supply’ consistent with the laws of physics? Professor Dr Arturs Lešinskis explains why cooling is not ‘cold transfer’ and why terminology in the energy sector must be scientifically sound.

Concepts such as “cold, cold energy, cold supply” do not exist in non-electrical physics, in the theory of heat transfer, or in technical thermodynamics; there is only heat and thermal energy, and only heat can be “transported”.

When cooling an object using compression-condensation, absorption, vapour ejection or thermoelectric cooling equipment, thermal energy or electrical energy is consumed to move heat from an environment with a lower temperature to an environment with a higher temperature.

Cooling – a process that reduces the temperature of any object or substance by removing thermal energy through heat conduction, convection or thermal radiation via thermal conductivity, convection and radiative heat transfer; When cooling an object using compression-condensation, absorption, vapour ejection or thermoelectric cooling equipment, thermal energy or electrical energy is consumed to transfer heat from a lower-temperature environment to a higher-temperature environment.

A refrigeration system – depending on its design and the technology used – ensures a reduction in temperature and/or the removal of thermal energy

Freezing – a cooling process to a temperature lower than the crystallisation point of the substance being cooled, or the liquefaction temperature of gases.

Freezing equipment – a system of equipment which, depending on its design, ensures the freezing or liquefaction of a substance.

Nevertheless, the Latvian Energy Law contains a provision that is incomprehensible and unjustified:

1⁴) residual cold — cold that is an unavoidable by-product generated in industrial installations, power stations or equipment used in the tertiary sector (the commercial and public services sector) where the cogeneration process is or will be used (even if the use of the cogeneration process is not feasible or the costs of installing cogeneration equipment exceed the benefits of using such equipment), and which, without access to a centralised cooling supply system, would be lost unused into the air or water; https://likumi.lv/ta/id/49833-energetikas-likums

An explanation has long been provided: We must begin with the basic concepts, terms and their definitions in Physics, the theory of heat transfer and technical thermodynamics:

1. By the concept of temperature, we understand and describe the average kinetic energy of the chaotic motion of a substance’s molecules. Consequently, zero degrees would be the case if the molecules were not moving. However, according to our understanding of the structure of the world, matter without motion is inconceivable and energy does not tend to have a negative sign. Temperature is measured on the absolute temperature scale in degrees Kelvin. In everyday life, it is more common to express temperature using the emotionally charged Celsius or Fahrenheit scales, because as winter approaches, people start to feel the cold, and this is, of course, a negative experience.
2. Any body above absolute zero emits its inherent heat in the form of electromagnetic waves and transfers it via heat conduction and convection. Consequently, heat naturally moves from an environment with a higher temperature to one with a lower temperature.
3. To move heat in the opposite direction, cooling equipment has been developed, and energy must be consumed. In the vast majority of cases, a compression-condensation cycle is used, where electrical energy is used to power the compressor. However, there is also the absorption cycle, where the cooling effect can be achieved using thermal energy.
4. Accordingly, cooling technologies are being developed and cooling equipment, devices, systems and units are being manufactured. If, as a result of cooling, the temperature of the substance or product being cooled is lowered to the temperature at which gases liquefy or liquids crystallise, this is referred to as freezing, and the technology, devices, equipment and units used for this are known as freezing technology, devices, equipment and units.
5. To generate electricity, the chemical energy of organic fuels is used in approximately 80% of cases. Nuclear energy is also used, as well as, in small quantities, energy from river hydropower, solar radiation, wind, tidal and wave energy. Mechanical energy is required to operate electric generators; this is obtained through rapid oxidation or combustion, converting the chemical energy of the fuel into thermal energy. This thermal energy is used to drive steam turbines or internal combustion engines.
6. Electricity generation processes that utilise the chemical or nuclear energy of fuel must be cooled. To get rid of excess heat, it is released into the atmosphere, discharged into an open water body, or sold to consumers for heating and domestic hot water production.
7. Fortunately, the excess heat can also be used to drive an absorption cooling cycle, and the resulting cooling effect, or cooling energy, can be sold for the cooling of certain facilities using district cooling systems. However, it must not be forgotten that the absorption cycle also generates excess heat, which must be discharged into the atmosphere or a water reservoir.
8. Thus, residual heat is always generated in production processes, and by using the absorption cycle, it is also possible to sell this as cooling energy.
9. The term ‘cold supply’ has no scientifically based explanation. It is a loanword from the Russian language.

When translating the Energy Law or any regulatory documents into English, this term should be translated as ‘centralised cooling system’.

Let us develop clear, scientifically sound terminology.

The precise use of terms helps not only to understand cooling processes, but also to plan, design and implement effective cooling systems in practice.