Heat Medium Tank Venting for Faster Air Removal in HVAC Circuits

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Solution Overview

Problem

Existing air-conditioning apparatuses face inefficiencies in eliminating air from conveyance passages, requiring lengthy processes and involving environmentally unfriendly wastewater treatment when using antifreeze solutions, which affects workability and economy.

Innovation Solution

An air-conditioning apparatus with an air discharge device including a heat medium tank and an air vent valve, allowing for efficient separation and discharge of air from the heat medium circuit, improving workability, economy, and environmental friendliness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If air is eliminated from the conveyance passage by operating the heat medium conveyance device and flow switching valve, then air can be discharged from the system, but the process requires lengthy operations and multiple steps reducing workability

Engineering Contradiction:
Improveair elimination effectivenessVSAvoidworkability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system is divided into a water circulation path and an antifreeze solution circulation path with separate conveyance devices. The air elimination process can be performed independently in each path, allowing parallel operation and reducing total elimination time while maintaining effective air removal from both circulation systems

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Air elimination is performed automatically during the heat medium introduction process before the system begins normal operation. The controller automatically operates the conveyance device and flow switching valve to eliminate air, so no separate manual air elimination step is needed, improving workability without compromising air removal effectiveness

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If antifreeze solution is used as heat medium to enable operation in low temperature environments, then the air-conditioning apparatus can operate in cold climates, but wastewater treatment is required which affects environmental friendliness and economy

Engineering Contradiction:
Improvelow temperature operation capabilityVSAvoidenvironmental friendliness
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The circulation system is segmented into water circulation paths and antifreeze solution circulation paths. Water is used in indoor units where it contacts living spaces, eliminating the need for wastewater treatment, while antifreeze solution is confined to outdoor units where it does not require treatment, maintaining environmental friendliness while enabling low temperature operation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The flow switching valve acts as an intermediary that directs the heat medium to appropriate circulation paths based on operating conditions. It enables the system to switch between water and antifreeze solution circulation, allowing the use of environmentally friendly water when possible while maintaining low temperature capability with antifreeze solution when needed

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If water is used as heat medium instead of antifreeze solution, then wastewater treatment is not required improving environmental friendliness, but the system cannot operate in low temperature environments

Engineering Contradiction:
Improveenvironmental friendlinessVSAvoidlow temperature operation capability
Core Design Contradiction:
Object-generated harmful factorsVSAdaptability or versatility

Solution Approach 1:

The air-conditioning apparatus is designed with multi-functionality to support both water circulation and antifreeze solution circulation modes. The system can adaptively select the appropriate heat medium based on ambient temperature and operational requirements, maintaining environmental friendliness with water while preserving low temperature capability with antifreeze solution

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically adjusts the type of heat medium circulated based on operating conditions. The controller monitors ambient temperature and automatically switches between water and antifreeze solution circulation paths, allowing the system to optimize for environmental friendliness when temperatures permit and for low temperature operation when necessary

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

The apparatus efficiently discharges air, reducing setup time and eliminating the need for wastewater treatment, thus enhancing workability and environmental sustainability while minimizing water usage.

Implementation Method 1

a heat medium conveyed by a heat medium conveyance device flows into the heat medium tank. At this time, due to a difference in density between the heat medium and air, air is lifted up to an upper part of the tank, and the heat medium stays in a lower part of the tank

Methodology Applied
Scientific EffectDensity difference separation: Density Gradient

Implementation Method 2

an air vent valve provided at the heat medium tank. The air vent valve discharges air to the outside of the air discharge device

Methodology Applied
Scientific EffectPressure-driven flow: Pressure Gradient

Data Source

PatentEP3217109B1Air conditioning device
Publication Date: 2021.09.22 MITSUBISHI ELECTRIC CORP
  • EP3217109B1 patent drawingFigure 1~2
  • EP3217109B1 patent drawingFigure 3~4
  • EP3217109B1 patent drawingFigure 5~6

AI summary

An air-conditioning apparatus includes a refrigerant circuit in which a compressor, a heat source side heat exchanger, an expansion device, and an intermediate heat exchanger exchanging heat between refrigerant and a heat medium are connected by a refrigerant pipe, the refrigerant flowing through the refrigerant circuit, a heat medium circuit in which a pump conveying the heat medium, a use side heat exchanger, and the intermediate heat exchanger are connected by a heat medium pipe, the heat medium flowing through the heat medium circuit, and an air discharge device including a heat medium tank connected to the heat medium circuit and separating air from the heat medium in the heat medium circuit, and an air vent valve provided at the heat medium tank and discharging the air.