B. When metals are heated, they expand due to the increased kinetic energy of their atoms, causing them to vibrate more and occupy more space. This expansion is accommodated in the transfer of hot liquids or in high-temperature surroundings through various engineering and structural mechanisms:
1. Expansion Joints: In pipelines or structures where hot liquids or gases flow through metal pipes, expansion joints are used. These joints are designed to absorb the expansion and contraction of the metal due to temperature changes without causing damage or deformation. They provide flexibility and allow the metal to expand or contract within a specific range.
2. Loose Fitting or Clearance: In some cases, especially in mechanical systems, parts may be assembled with a slight gap or clearance between them. This intentional gap allows for thermal expansion without causing binding or warping of the components. For instance, rails on bridges or train tracks are installed with small gaps to account for thermal expansion during temperature changes.
3. Thermal Insulation: Insulating materials are used around metal components or structures to regulate temperature changes. By minimizing the temperature difference between the metal and its surroundings, the extent of thermal expansion can be reduced, mitigating potential issues associated with excessive expansion.
4. Materials Selection: Engineers often select specific types of metals or alloys that exhibit lower coefficients of thermal expansion for applications where precise tolerances are critical. Alloys with lower expansion rates can help minimize the degree of expansion when exposed to high temperatures.
5. Design Considerations: Architects and engineers take thermal expansion into account during the design phase of structures or systems. They incorporate allowances for expansion in the design calculations to prevent stress buildup or structural failure caused by thermal expansion.
In summary, various techniques such as using expansion joints, allowing clearance, employing insulation, selecting appropriate materials, and careful design considerations are employed to accommodate the expansion of metals in systems involving hot liquids or high-temperature environments. These measures help prevent damage, distortion, or failure of structures or components due to thermal expansion.
