Suction stabilizer control circuit for a heat pump system

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Solution Overview

Problem

Heat pump systems face efficiency losses due to the need for significant superheating to prevent liquid refrigerant from reaching the compressor, which results in subcooling at the condenser and increased energy consumption.

Innovation Solution

A suction stabilizer control circuit (SSCC) is introduced, comprising a thermostatic expansion valve (TXV), a TXV bypass line, and a metered orifice, which divides refrigerant flow to reduce subcooling and superheating by bypassing a portion of the refrigerant around the TXV, allowing for optimized refrigerant delivery to the evaporator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If significant superheating is applied to prevent liquid refrigerant from reaching the compressor, then compressor protection is improved, but system efficiency deteriorates due to subcooling at the condenser and increased energy consumption

Engineering Contradiction:

Improvecompressor protectionVSAvoidsystem efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The refrigerant flow is divided into two separate paths: one path goes through the TXV which provides compressor protection by controlling superheat, while the other path bypasses the TXV through the bypass line to reduce subcooling losses. This segmentation allows the system to simultaneously achieve both compressor protection and improved efficiency by optimizing each path's function independently

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The suction stabilizer control circuit acts as an intermediary device that combines the refrigerant flows from the TXV path and the bypass path. It stabilizes the suction pressure and ensures that the combined flow maintains adequate superheat protection while minimizing the subcooling penalty, thus mediating between the conflicting requirements of reliability and efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If significant superheating is applied at the evaporator outlet, then compressor protection is improved, but condenser activity and system capacity deteriorate

Engineering Contradiction:

Improvecompressor protectionVSAvoidsystem capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

By segmenting the refrigerant flow into two paths with different superheat levels, the system can maintain the minimum required superheat for compressor protection while allowing the bypass path to operate with lower superheat, thereby improving condenser activity and overall system capacity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the superheat parameter differently for the two flow paths: the TXV path maintains high superheat for protection, while the bypass path uses lower superheat to improve heat exchange efficiency. The control circuit dynamically adjusts the flow distribution based on system conditions to optimize the balance between protection and capacity

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a TXV is used to prevent liquid refrigerant from leaving the evaporator outlet, then compressor protection is improved, but subcooling at the condenser increases causing efficiency losses

Engineering Contradiction:

Improvecompressor protectionVSAvoidcondenser subcooling losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The system segments the refrigerant flow so that only a portion passes through the TXV while the remainder bypasses it. This reduces the overall superheat requirement and minimizes condenser subcooling losses while still maintaining adequate compressor protection through the TXV path

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of applying full superheat protection to all refrigerant flow, the system applies partial protection only to the portion passing through the TXV. The bypass portion operates with minimal superheat, reducing the total energy penalty while still achieving the necessary protection level when the paths are combined

Inventive Principle:

Principle #16Partial or excessive action

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

The SSCC reduces superheating at the evaporator to as low as 4 degrees Fahrenheit, enhancing condenser activity, system capacity, and efficiency while maintaining compressor protection from liquid refrigerant, thereby stabilizing suction pressure and minimizing energy losses.

Implementation Method 1

The sensing line 160 is filled with a sensing line refrigerant, more or less of which will vaporize depending on the amount of refrigerant superheat present at the evaporator outlet 124

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

Methodology Applied

Scientific EffectFluid flow division:

Implementation Method 3

A suction stabilizer control circuit (SSCC) is introduced, comprising a thermostatic expansion valve (TXV), a TXV bypass line, and a metered orifice

Methodology Applied

Scientific EffectFlow restriction through orifice:

Data Source

PatentUS10557653B1Suction stabilizer control circuit for a heat pump system

Publication Date: 2020.02.11 BUSCHUR JEROME

AI summary

In a heat pump system, a suction stabilizer control circuit (SSCC) reduces or eliminates subcooling at the condenser and reduces superheating needed for compressor protection at the evaporator. The SSCC includes a bypass line that bypasses a predetermined portion of flow through a refrigerant liquid transport line around a thermostatic expansion valve (TXV).