Indoor Unit Heat Exchanger Layout for Lower Coil Airflow

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Solution Overview

Problem

Conventional air conditioner indoor units with fin-tube heat exchangers face issues of insufficient wind velocity at lower heat exchangers due to louvered portions, leading to increased fan input and reduced heat transfer performance, while also complicating assembly and increasing noise.

Innovation Solution

The indoor unit design features a fin-tube type heat exchanger with varying air pressure loss across sections, where the adjacent heat exchanger near the air inlet has a larger pressure loss than the remote heat exchanger, ensuring sufficient wind velocity and reducing fan input, while omitting louvered portions on the lower front heat exchanger to enhance heat transfer and assembly efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If louvered portions are provided in the first and second rows of the heat exchanger, then heat transfer performance is enhanced, but wind velocity at the lower heat exchanger becomes insufficient and fan input increases

Engineering Contradiction:

Improveheat transfer performanceVSAvoidwind velocity

Core Design Contradiction:

TemperatureVSSpeed

Solution Approach 1:

The patent applies local quality by providing louvered portions only in specific locations (first row on windward side, second row on both sides) rather than uniformly across all fins. This localized approach enhances heat transfer at critical areas while maintaining sufficient wind velocity in other regions, resolving the contradiction between heat transfer performance and wind velocity.

Inventive Principle:

Principle #3Local quality

2Temperature

If louvered portions are provided on both sides of fins in the second row, then heat transfer performance is improved, but air flow is separated by fan blades and fan input increases

Engineering Contradiction:

Improveheat transfer performanceVSAvoidfan input

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The patent provides louvered portions on both sides of fins only in the second row, not in the first row on the leeward side. This selective local quality approach optimizes heat transfer where needed while avoiding excessive air flow separation that would increase fan energy consumption.

Inventive Principle:

Principle #3Local quality

3Temperature

If wind velocity at the lower heat exchanger is insufficient, then heat transfer performance decreases, but fan input increases to compensate

Engineering Contradiction:

Improveheat transfer performanceVSAvoidfan input

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The patent changes the physical parameters of the heat exchanger by introducing louvered portions with specific geometries and distributions. This modifies the air flow characteristics and pressure distribution across the heat exchanger, ensuring sufficient wind velocity at the lower section while maintaining efficient heat transfer, thereby avoiding increased fan input.

Inventive Principle:

Principle #35Parameter changes

4Productivity

If condensed water concentrates at the upper ends of the fins, then drainage efficiency decreases, but modifying fin structure to prevent concentration may reduce heat transfer performance

Engineering Contradiction:

Improvedrainage efficiencyVSAvoidheat transfer performance

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent applies local quality by omitting louvered portions at specific locations (uppermost front portion in lower heat exchanger) where condensed water tends to concentrate. This localized modification prevents water accumulation and improves drainage efficiency without significantly impacting the overall heat transfer performance of the heat exchanger.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration achieves improved wind velocity, reduced fan input, increased heat transfer performance, and simplified assembly, while also reducing noise and increasing drain efficiency for condensed water.

Implementation Method 1

a fin-tube type heat exchanger used for exchanging heat between fluid such as air

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

heat transfer tubes extending through stacked plate fins

Methodology Applied

Scientific EffectConduction (thermal): Conduction (thermal)

Implementation Method 3

The air pressure loss of an adjacent heat exchanger disposed adjacent to the air inlet is larger than the air pressure loss of a remote heat exchanger

Methodology Applied

Scientific EffectPressure Gradient: Pressure Gradient

Data Source

PatentUS8156999B2Indoor unit of air conditioner

Publication Date: 2012.04.17 MITSUBISHI ELECTRIC CORP

AI summary

This invention relates to an air conditioner having an air inlet at its upper portion. The heat exchanger (4) includes multiple plate fins (1) arranged in parallel so that air flows therebetween, and heat transfer tubes (2) perpendicularly inserted into the plate fins (1) and arranged perpendicularly to the air flow direction through which working fluid passes. The heat exchanger (4) includes a lower front heat exchanger (4a), an upper front heat exchanger (4b), and a rear heat exchanger (4c) separately produced and arranged to surround the circulating fan (5). The air pressure loss of the lower front heat exchanger (4a) is set to be smaller than the air pressure losses of the other heat exchangers.