Heat Pump Charge Imbalance Correction Using Tank and Three-Way Valve

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Solution Overview

Problem

Heat pump systems with smaller indoor coils experience undesirable pressure increases when switching from cooling to heating mode, leading to inefficiencies and potential system failures.

Innovation Solution

A charge imbalance correction apparatus is introduced, featuring a tank and a modified reversing valve that temporarily stores refrigerant during the heating mode to reduce pressure, and returns it during the cooling mode to maintain system balance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a smaller indoor coil is used, then the heat pump system can operate in heating mode, but the condensing side pressure undesirably increases when switching modes

Engineering Contradiction:

Improveheating mode operationVSAvoidcondensing side pressure

Core Design Contradiction:

Adaptability or versatilityVSStress or pressure

Solution Approach 1:

A reversing valve is introduced as an intermediary component to control refrigerant flow direction. The valve includes a body with a suction port, discharge port, first coil, and second coil, enabling it to mediate between the outdoor coil and indoor coil to switch between cooling and heating modes while managing pressure distribution

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the operational parameters of the refrigerant by utilizing phase changes and pressure differential changes. During mode switching, the refrigerant undergoes pressure changes as it moves between high-pressure and low-pressure sides, with the reversing valve facilitating these parameter transitions to prevent unwanted pressure increases

Inventive Principle:

Principle #35Parameter changes

2Productivity

If refrigerant is stored in the outdoor coil during cooling mode, then the system operates efficiently in cooling, but pressure increases when switching to heating mode

Engineering Contradiction:

Improvecooling mode efficiencyVSAvoidsystem pressure during mode switch

Core Design Contradiction:

ProductivityVSStress or pressure

Solution Approach 1:

The reversing valve operates dynamically to switch refrigerant flow paths between cooling and heating modes. The valve's movable components (such as a plunger or valve core) change position based on operational mode requirements, enabling dynamic adaptation of the refrigerant circulation path to maintain pressure balance during transitions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The refrigerant undergoes phase transitions between liquid and vapor states as it moves through the system. During mode switching, the refrigerant's phase change helps regulate pressure, with the reversing valve positioned to facilitate these transitions and prevent pressure surges in the condensing side

Inventive Principle:

Principle #36Phase transitions

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 apparatus effectively mitigates pressure increases in heat pump systems with smaller indoor coils, ensuring efficient operation and extending the system's lifespan by maintaining optimal refrigerant flow and pressure balance across modes.

Implementation Method 1

temporarily storing, in a heating mode of a heat pump system, refrigerant from the heat pump system within a tank to reduce a pressure within the heat pump system

Methodology Applied

Scientific EffectPressure reduction through refrigerant storage:

Implementation Method 2

providing the liquid refrigerant conduit in fluid communication with the tank through the valve

Methodology Applied

Scientific EffectPressure differential driven flow: Pressure Gradient

Implementation Method 3

transferring heat from the building to an external environment on warm days and warms the building by drawing heat from the external environment into the building on cool days

Methodology Applied

Scientific EffectHeat transfer through refrigerant phase change: Phase Change

Implementation Method 4

the outdoor coil operates as a condenser and the indoor coil operates as an evaporator

Methodology Applied

Scientific EffectHeat exchange through condensation and evaporation: Condensation

Data Source

PatentUS20250067486A1Systems and Methods for Charge Imbalance Correction in Heat Pumps

Publication Date: 2025.02.27 RHEEM MFG CO

AI summary

Systems and methods are provided for charge imbalance correction in heat pumps. Particularly, a tank may be provided between a vapor conduit and a liquid refrigerant conduit of a heat pump that may be used to temporarily store at least some of the refrigerant when the heat pump is in a heating mode. When the heat pump transitions back to a cooling mode, the refrigerant may be returned back into the heat pump. The flow of refrigerant to and from the tank may be regulated by a three-way valve. The valve is connected to the vapor conduit through one port, the tank through a second port, and the liquid refrigerant conduit through a third port. The valve includes a spring and a slide with a cut-out region that allows two of the three ports to be in fluid communication depending on a position of the slide within the valve.