Integrated Heat Pump Refrigerant Charge Control Across Operating Modes

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Solution Overview

Problem

Heat pumps face challenges in managing refrigerant charge across multiple modes of operation, leading to inefficiencies and potential compressor damage due to insufficient or excessive refrigerant levels.

Innovation Solution

An integrated system that uses a reversing valve and charge adjustment valve to selectively couple inactive and active lines, allowing for the transfer of refrigerant between them to optimize the refrigerant charge, ensuring it remains within desired thresholds in both dedicated water heating and space cooling/water heating modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an accumulator is added to prevent compressor damage from liquid compression, then compressor reliability is improved, but refrigerant charge management complexity increases

Engineering Contradiction:

Improvecompressor reliabilityVSAvoidrefrigerant charge management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system uses the existing expansion valves and charge adjustment valve to self-regulate refrigerant charge distribution and prevent liquid accumulation in the compressor suction line. The control system monitors operational mode and automatically adjusts valve positions to maintain proper refrigerant levels, eliminating the need for a separate accumulator while maintaining compressor protection. This resolves the contradiction by providing protection through intelligent control rather than additional hardware.

Inventive Principle:

Principle #25Self-service

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 solution enables the heat pump to operate efficiently across multiple modes by maintaining optimal refrigerant levels, extending its operational limits and improving efficiency by adjusting refrigerant charge as needed.

Implementation Method 1

Here, the condensed refrigerant is expanded and vaporized and absorbs heat from an outdoor heat sink at the outdoor heat exchanger

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 2

The compressor provides refrigerant vapor to the water heat exchanger

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

High pressure refrigerant gas from the compressor is directed to the water heat exchanger, where the refrigerant gas is condensed and heat is transferred to a domestic water supply

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 4

heat is transferred to a domestic water supply

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentUS10168087B2Refrigerant charge management in an integrated heat pump

Publication Date: 2019.01.01 UT BATTELLE LLC

AI summary

A heat pump including an integrated system for the management of refrigerant charge is provided. The heat pump includes an indoor line and an outdoor line that are connected to a compressor through a reversing valve. Refrigerant charge is managed by coupling the inactive line to the suction side of the compressor. For example, the heat pump can include an expansion valve to couple the inactive line to the compressor to supplement the flow-rate of refrigerant. The heat pump is operable in a dedicated water heating mode and a space cooling and water heating mode in some embodiments, while other modes of operation are contemplated in other embodiments.