Question

A Sankey diagram is primarily used to represent

• A. Temperature distribution in a furnace
• B. Pressure drops in a piping system
• C. Energy balance and heat flow distribution
• D. Electrical wiring diagrams

Hint:

Whenever you see a question about a Sankey Diagram in a thermal or energy management context, always look for keywords like Energy Balance, Heat Flow, or Energy Auditing. The defining characteristic is: Arrow Width \(\propto\) Flow Magnitude.

Answer 1

The Correct Option is C

Concept: A Sankey diagram is a specialized type of flow diagram in which the width of the visual bands or arrows is strictly proportional to the quantity of flow. While it can be applied to various materials or monetary resources, its primary and most widespread engineering application is in thermal and industrial systems to visually map energy inputs, useful energy outputs, and various components of energy losses. Detailed Explanation:
When performing an energy audit of a plant, process, or individual unit operations (such as an industrial boiler or furnace), it is essential to trace how energy enters the system and where it is allocated or lost. A Sankey diagram provides an immediate visual summary of the First Law of Thermodynamics (Energy Conservation): \[ \sum \text{Energy Input} = \sum \text{Energy Output} \] The main features of a Sankey diagram used in energy balance systems include:
• Source/Input: A wide consolidated arrow representing the total energy input (e.g., fuel chemical energy + electrical power input).
• Branching Flows: As the energy proceeds through the process, the main arrow splits into smaller paths. The width of each path corresponds directly to its energy magnitude.
• Loss Visualization: Paths representing flue gas losses, radiation losses, and cooling water heat extraction branch off laterally, allowing engineers to identify major areas of thermal degradation instantly. Evaluating the alternative options:
• Option (1) is incorrect: Temperature profiles or spatial distributions inside a furnace are typically modeled and visualized using contour plots or multi-dimensional profile graphs generated via Computational Fluid Dynamics (CFD).
• Option (2) is incorrect: Pressure drops through structural networks and piping systems are mapped using hydraulic grade lines or schematic piping diagrams labeled with local pressure values.
• Option (4) is incorrect: Electrical wiring pathways are represented by schematic circuit diagrams showing physical or logical connectivity rather than scale-proportional resource flows. Thus, a Sankey diagram is uniquely tailored for tracking energy balance and heat flow distributions.