Bypass-Pipe Heat Exchanger Layout for Lower Pressure Loss

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Solution Overview

Problem

The existing heat exchanger designs face increased pressure loss and poor lubricating oil drainage when operating as an evaporator, leading to reduced defrosting performance and oil stagnation issues due to the header and heat transfer tube configuration.

Innovation Solution

Incorporating a first bypass pipe that communicates with the header at a middle portion and the refrigerant pipe, with one end connected to the lower header portion, to distribute refrigerant flow and reduce pressure loss, while allowing lubricating oil to be recirculated.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the header communicates with heat transfer tubes at side portions to improve defrosting performance, then defrosting performance is improved, but pressure loss increases

Engineering Contradiction:

Improvedefrosting performanceVSAvoidpressure loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The header is divided into multiple communication portions (first communication portion and second communication portion) at different heights, allowing refrigerant to be distributed to different regions. This segmentation enables optimized flow paths that reduce pressure loss while maintaining defrosting capability in lower regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A refrigerant communication pipe is introduced as an intermediary component to connect the header to the refrigerant inlet. This intermediary allows flexible routing of refrigerant flow, enabling the system to achieve both good defrosting performance and reduced pressure loss by optimizing the communication path.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the header communicates with heat transfer tubes at side portions to improve defrosting performance, then defrosting performance is improved, but lubricating oil stagnation occurs

Engineering Contradiction:

Improvedefrosting performanceVSAvoidlubricating oil stagnation

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The header's communication structure is segmented into multiple portions at different heights, creating varied flow paths that prevent oil from settling in one location. The first communication portion at a lower height and the second at a higher height work together to maintain continuous oil circulation while achieving defrosting.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The refrigerant flow path is made dynamic through the multi-level communication portions, allowing the flow direction and distribution to adapt. This dynamic flow pattern prevents oil stagnation by continuously moving oil through the system while maintaining effective defrosting in lower regions.

Inventive Principle:

Principle #15Dynamics

3Productivity

If heat transfer tubes are arranged vertically with header communication to improve heat exchange, then heat exchange efficiency is improved, but pressure loss increases

Engineering Contradiction:

Improveheat exchange efficiencyVSAvoidpressure loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

Different regions of the heat exchanger are given different communication qualities through the first and second communication portions at different heights. This local differentiation allows lower regions to receive refrigerant for defrosting while upper regions maintain efficient heat exchange, optimizing both functions without excessive pressure loss.

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 enhances defrosting performance, reduces pressure loss, and minimizes lubricating oil stagnation by optimizing refrigerant flow and oil circulation within the heat exchanger.

Implementation Method 1

a first bypass pipe having ends one of which communicates with a lower portion of the header and the other of which communicates with a middle portion of the refrigerant pipe

Methodology Applied

Scientific EffectPressure loss reduction through bypass flow:

Implementation Method 2

a plurality of heat transfer tubes arranged at predetermined intervals in a vertical direction

Methodology Applied

Scientific EffectHeat transfer: Heat Exchanger

Implementation Method 3

a refrigerant pipe that communicates with the header at a middle portion of the header in the vertical direction

Methodology Applied

Scientific EffectFluid flow:

Data Source

PatentUS11193701B2Heat exchanger and refrigeration cycle apparatus

Publication Date: 2021.12.07 MITSUBISHI ELECTRIC CORP

AI summary

A heat exchanger includes a plurality of heat transfer tubes arranged at predetermined intervals in a vertical direction, a tubular header that has a plurality of connection portions where the heat transfer tubes are connected to a side portion of the header and that communicates with each of the heat transfer tubes, a refrigerant pipe that communicates with the header at a middle portion of the header in the vertical direction, and a first bypass pipe having ends one of which communicates with a lower portion of the header and the other of which communicates with a middle portion of the refrigerant pipe. A distance between a communication position at which the first bypass pipe and the refrigerant pipe communicate with each other and an inner wall of the header is not more than double an inside diameter of the refrigerant pipe.