Receiver Pressure Control During Gas Bypass Valve Malfunction

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Solution Overview

Problem

Vapour compression systems, such as refrigeration and heat pump systems, face instability and shutdowns due to malfunctioning or saturated gas bypass valves, leading to inadequate cooling or heating capacity and costly service interruptions.

Innovation Solution

A method to control the vapour compression system by registering gas bypass valve malfunctions or saturation, obtaining pressure values within the receiver, and adjusting the gaseous refrigerant supply to maintain a target pressure level, ensuring continued operation until repairs can be made.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the gas bypass valve is used to control mass flow of gaseous refrigerant, then the system can adapt to ambient conditions and provide required cooling or heating capacity, but the system becomes unstable or shuts down when the valve malfunctions or saturates

Engineering Contradiction:

Improveadaptability to ambient conditionsVSAvoidsystem stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system changes the control parameter from gas bypass valve opening degree to receiver pressure. By monitoring receiver pressure and adjusting the high pressure expansion device accordingly, the system maintains stable operation even when the gas bypass valve malfunctions or saturates, thus resolving the contradiction between adaptability and reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The receiver pressure serves as an intermediary parameter between the gas bypass valve control and the actual refrigerant mass flow. By controlling receiver pressure through the high pressure expansion device, the system indirectly manages refrigerant flow without directly relying on the potentially malfunctioning gas bypass valve, thereby maintaining system stability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If a small capacity gas bypass valve is selected for receiver compressor systems, then the valve size matches the normal refrigerant flow, but the valve saturates when receiver compressors go into alarm

Engineering Contradiction:

Improvevalve size matchingVSAvoidvalve capacity adequacy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Instead of making the gas bypass valve larger to handle emergency flows, the system inverts the control approach by using the high pressure expansion device to control refrigerant supply to the receiver. This allows the small capacity valve to remain small while the expansion device handles the additional flow control responsibility during alarm conditions

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The high pressure expansion device takes on multiple functions: it controls refrigerant flow to the receiver during normal operation and also provides emergency flow control when receiver compressors alarm. This multi-functionality eliminates the need for an oversized gas bypass valve, resolving the contradiction between device complexity and reliability

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If the system shuts down immediately upon detecting gas bypass valve malfunction, then system safety is maintained, but productivity and operational continuity are lost

Engineering Contradiction:

Improvesystem safetyVSAvoidoperational continuity

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The system converts the harmful effect of gas bypass valve malfunction into a beneficial opportunity to implement alternative control through receiver pressure management. By using the high pressure expansion device to control refrigerant supply based on receiver pressure, the system maintains safe operation while continuing productivity, turning a potential shutdown scenario into a demonstrated backup control capability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS10962262B2Method for controlling a vapour compression system during gas bypass valve malfunction

Publication Date: 2021.03.30 DANFOSS AS

AI summary

A method for controlling a vapour compression system (1) is disclosed, the vapour compression system (1) comprising at least one compressor (2, 16), a heat rejecting heat exchanger (3), a high pressure expansion device (4, 15, 17), a receiver (5), an evaporator expansion device (6), an evaporator (7) and a gas bypass valve (8), arranged in a refrigerant path. It is registered that the gas bypass valve (8) is malfunctioning or saturated, and a pressure value for a pressure prevailing inside the receiver (5) is obtained. Finally, the vapour compression system (1) is controlled in order to control a gaseous refrigerant supply to the receiver (5) to adjust the pressure prevailing inside the receiver (5) to reach a target pressure level.