HVACR Variable Speed Compressor with Dynamic High-Side Volume Control

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Solution Overview

Problem

HVACR systems face inefficiencies when using variable speed compressors, as refrigerant flow rates drop at low speeds, leading to inconsistent refrigerant flow and increased pressure at high speeds, which can cause components to operate suboptimally and reduce system efficiency.

Innovation Solution

Incorporating a second heat exchanger that adjusts refrigerant flow to manage high side pressure by directing refrigerant away from or through the heat exchanger based on compressor speed, effectively expanding or reducing the system's volume to maintain efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a variable speed compressor operates at high speed, then cooling capacity increases, but refrigerant pressure increases causing components to operate suboptimally

Engineering Contradiction:

Improvecooling capacityVSAvoidrefrigerant pressure

Core Design Contradiction:

ProductivityVSStress or pressure

Solution Approach 1:

The system dynamically adjusts the volume of the high pressure side by controlling the three-way valve to direct refrigerant flow. When the variable speed compressor operates at high speed, the valve directs refrigerant through the second heat exchanger to increase high pressure side volume, thereby reducing refrigerant pressure and preventing suboptimal component operation while maintaining high cooling capacity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the physical parameter of high pressure side volume by routing refrigerant through different paths. The three-way valve switches between directing refrigerant directly to the load (smaller volume) or through the second heat exchanger (larger volume), thereby adjusting system parameters to optimize performance at different compressor speeds.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If a variable speed compressor operates at low speed, then energy consumption decreases, but refrigerant flow rate drops leading to inconsistent flow

Engineering Contradiction:

Improveenergy consumptionVSAvoidrefrigerant flow consistency

Core Design Contradiction:

Loss of energyVSStability of the object's composition

Solution Approach 1:

The system dynamically adjusts the refrigerant flow path based on compressor speed. When the variable speed compressor operates at low speed, the three-way valve directs refrigerant away from the second heat exchanger to maintain consistent flow through the primary path, ensuring stable operation while preserving energy efficiency.

Inventive Principle:

Principle #15Dynamics

3Stress or pressure

If the high pressure side volume is increased, then refrigerant pressure decreases improving component operation, but system volume increases

Engineering Contradiction:

Improverefrigerant pressureVSAvoidsystem volume

Core Design Contradiction:

Stress or pressureVSVolume of stationary object

Solution Approach 1:

Rather than permanently increasing system volume, the patent implements a dynamic adjustment mechanism using a three-way valve that can expand the high pressure side volume by routing refrigerant through the second heat exchanger only when needed. This allows the system to maintain compact size while achieving pressure optimization on demand.

Inventive Principle:

Principle #15Dynamics

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 allows for consistent refrigerant flow and pressure management, improving system efficiency by expanding the high pressure side volume at high compressor speeds and reducing it at low speeds, preventing refrigerant backup and maintaining efficient operation across varying compressor speeds.

Implementation Method 1

The high side heat exchanger removes heat from a refrigerant. The second heat exchanger removes heat from the refrigerant.

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

The high side heat exchanger removes heat from a refrigerant. The second heat exchanger removes heat from the refrigerant.

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

The variable speed compressor compresses the refrigerant from the load and directs the compressed refrigerant to the high side heat exchanger.

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS11408652B2Heating, ventilation, air-conditioning, and refrigeration system with variable speed compressor

Publication Date: 2022.08.09 LENNOX IND INC

AI summary

An apparatus includes a high side heat exchanger, a second heat exchanger, a load, a variable speed compressor, and a three-way valve. The high side heat exchanger removes heat from a refrigerant. The second heat exchanger removes heat from the refrigerant. The load uses the refrigerant to remove heat from a space proximate the load. The variable speed compressor compresses the refrigerant from the load and directs the compressed refrigerant to the high side heat exchanger. The three-way valve, when operating in a first mode, directs the refrigerant from the high side heat exchanger to the load and when operating in a second mode, directs the refrigerant from the high side heat exchanger to the second heat exchanger.