Heat Transfer and Solar Heating

Heat Transfer

• Heat transfer can occur through conduction, radiation, and convection.
• Conduction is the transfer of heat between objects in physical contact.
• Radiation is the transfer of heat through electromagnetic waves.
• Convection is the transfer of heat through the movement of fluids.

Solar Heating and Air Movement

• Solar heating causes air to expand and rise, creating an area of low pressure near the surface.
• This leads to the movement of air from high-pressure areas to low-pressure areas.

Specific Heat Capacity

• The specific heat capacity of a material is the amount of heat energy required to change the temperature of 1 kg of the material by 1°C.
• The specific heat capacity of concrete is 880 J/kg°C.
• The specific heat capacity of grass is 800 J/kg°C.

Refrigeration

• The refrigeration process involves the compression of a gas, which increases its temperature.
• The pressurized gas is then forced into coils, where it transfers heat to the outside air through conduction.
• The phase of the gas changes from gas to liquid as heat is transferred to the outside air.
• The term used to describe the transition from gas to liquid is condensation.

Latent Heat of Vaporisation

• The latent heat of vaporisation is the energy required to change the phase of a substance from liquid to gas.
• The latent heat of vaporisation of R-134a is 2.17 x 10^5 J/kg.

Coefficient of Volume Expansion

• The coefficient of volume expansion of a material is the change in volume per unit change in temperature.
• The coefficient of volume expansion of R-134a is 3.24 x 10^-3 °C^-1.

Giraffe Adaptations

• Giraffes have adaptations to help them survive in the desert, such as networks of blood vessels that bring warm blood to the skin.
• Heat is transferred from the blood to the skin through thermal radiation.
• Evaporation of water on the skin cools the blood beneath the skin.

Bridges and Expansion Joints

• Expansion joints on bridges allow for the expansion and contraction of the bridge material with changes in temperature.
• The coefficient of linear expansion of steel is 12 x 10^-6 °C^-1.

Temperature Measurement

• Thermal equilibrium is the state in which the temperatures of two or more systems are equal.
• The specific heat capacity of water is 4180 J/kg°C.
• The specific heat capacity of copper is 390 J/kg°C.

Latent Heat of Vaporisation and Steam

• The latent heat of vaporisation of steam is 2.25 x 10^6 J/kg.
• The energy used to produce steam can be calculated by measuring the mass of steam produced and the temperature of the steam.