Cold plays an essential role in our modern lives
Cold plays an essential role in our modern lives, from the comfort of air-conditioned spaces during scorching summers to preserving food and medicine in refrigerators. But have you ever stopped to ask: can we create cold? Let’s explore the science behind this concept.
The concept of cold has intrigued humans for centuries. Ancient civilizations first defined cold through its sensory effects and practical applications. The ancient Greeks were among the first to philosophize about cold. Aristotle described it as one of the fundamental qualities of matter, opposing heat and integral to the balance of nature [1]. The word “cold” itself traces back to the Proto-Indo-European root gel-, meaning “to freeze,” which evolved through the Proto-Germanic kaldjon to the Old English cald or ceald [2].
These early ideas may seem simple today, but they laid the foundation for understanding cold as more than just a feeling. They helped frame it as a physical phenomenon tied to the absence of heat, setting the stage for later scientific exploration.
Cold, in its simplest form, is defined as the absence of heat, characterized by low temperatures resulting from reduced molecular motion [3].
Temperature itself is a measure of the average kinetic energy—think of it as the speed—of particles within a substance. Higher temperatures correspond to faster-moving particles, while lower temperatures correspond to slower-moving particles [4]. When heat energy is removed from a substance, the motion of its particles slows down. This reduction in particle movement leads to the state we recognize as cold. For example, in ice, molecules vibrate within a fixed structure because they lack sufficient energy to break free and move freely [5].
Therefore, cold is not something that is created. It is a state we achieve by removing heat energy from a system.
Cold is achieved by removing or transferring heat from one place to another. Heat transfer, the mechanism behind this process, occurs in three primary ways. Each can be observed when cooling something, like your favourite drink:
The most common way to refrigerate items is through vapor-compression refrigeration systems, widely used in technologies like freezers, coolers, and air conditioners. This cycle relies on a refrigerant, a substance that absorbs and releases heat to create cooling effects. The process involves four key steps:
Understanding the concept of cold and how it is achieved sheds light on the critical technologies we often take for granted, such as refrigerators, air conditioners, and industrial cooling systems. These systems don’t create cold; they extract heat, a process that requires a significant amount of energy. For instance, air conditioning alone accounts for about 7% of global electricity consumption, and it’s expected to grow in the coming years. [6]
Traditional systems often rely on refrigerants with a high environmental impact, contributing to greenhouse gas emissions and climate change. As the planet heats up, the
demand for cooling systems rises, creating a vicious cycle where increased
cooling contributes to further warming. This makes improving the efficiency and
sustainability of these systems an urgent priority.
But can we make these systems better? Well, we’re on it! At HydroCool, we’re tackling these challenges by using CO₂, an eco-friendly refrigerant, and innovating with more efficient and sustainable cooling methods.
Would you like to learn more? We’ll be back with more cooling topics soon, so be sure to check back.
Sources:
[1] Classical element – Wikipedia
[2] cold | Etymology of cold by etymonline
[6] Air conditioning causes around 3% of greenhouse gas emissions. How will this change in the future? – Our World in Data
Author: Guillem Figueras
Editorial: Lucía Salinas
