Engineering Principles: Bicycles and Refrigeration

Essential Connectors and Vocabulary

But (pero), such as (tal como), actually (en realidad).

Despite (a pesar de), although (aunque), namely (es decir).

In addition (además de), so (tan, entonces, así).

Bicycle Design: Conventional vs. Improvements

• Conventional: Spoke wheels — Improvement: Disc wheels
• Conventional: Gear lever on the frame — Improvement: Combined gear change and brake
• Conventional: Tubular aluminium-alloy frame — Improvement: Carbon fibre frame
• Conventional: Pedals with toe-clips — Improvement: Clipless pedals
• Conventional: Steel gears — Improvement: Precision-engineered titanium gears
• Conventional: Ordinary handlebars — Improvement: Aerodynamic handlebars

Reasons for Engineering Improvements

• Reduce the wind resistance.
• Reduce time to switch between applying the brakes and changing gears.
• They are safe and operate like ski-bindings.
• Increase the speed the gear changes and decrease the chances of slipping a gear.
• Reduce the rider's wind resistance.

Fundamental Principles of Physics and Refrigeration

• When a liquid is heated, it changes to a gas.
• When a gas is cooled, it changes to a liquid.
• When a gas expands, it cools down.
• When a gas is compressed, it heats up.
• When a force is applied to a body, there is an equal and opposite reaction.
• When a current passes through a wire, it sets up a magnetic field around the wire.
• When a wire cuts a magnetic field, a current is induced in the wire.
• When pressure is applied to the surface, it extends in proportion.

Ordering the Refrigeration Process

1. The gas is compressed.
2. The gas passes through the condenser.
3. The gas condenses back into a liquid.
4. The liquid passes through a capillary tube.
5. The high pressure is maintained.
6. The liquid enters the evaporator.
7. The liquid turns into vapour.
8. The vapour is sucked back into the compressor.

Aerodynamics in Bicycles and Aircraft

• Racing bicycles and aircraft are designed to minimize wind resistance and maximize energy efficiency.
• The main part of a bicycle is the frame.
• The frame absorbs bumps.
• The wings convert energy power into lift.
• The wings absorb turbulence.
• Materials used in both: titanium, alloys, and carbon fibres.
• Racing bicycles and airplanes have in common the materials and design features.

Step-by-Step Refrigeration Cycle

1. First: The gas passes through the compressor, where it is compressed.
2. Then: It passes through the condenser, where it is condensed.
3. Next: The liquid passes through a capillary tube, where the pressure is maintained.
4. After that: The liquid enters the evaporator, where the liquid is turned into vapour.
5. Finally: The cold vapour is sucked back into the compressor, where it is compressed again.