Indoor Unit Heat-Medium Buffering During HVAC Faults
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Solution Overview
Problem
In multi-unit air-conditioning systems, if an abnormality occurs in one unit, it often leads to immediate stoppage of other units, disrupting cooling or heating operations, especially in critical spaces like server rooms where temperature stability is crucial.
Innovation Solution
The air-conditioning apparatus employs a heat medium, such as water or anti-freezing fluid, that acts as a buffer to delay stoppage of indoor units by maintaining temperature within a predetermined range, even if an abnormality occurs in the heat-source device or relay unit, using a controller to manage operations and continue cooling or heating as long as the temperature remains within the set range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refrigerant is supplied directly from heat-source device to indoor units, then cooling or heating operation is achieved, but immediate stoppage occurs in all units when abnormality is detected in any unit
Solution Approach 1:
The system is divided into independent operational segments: heat-source device, relay unit with intermediate heat exchanger, and indoor units. This segmentation allows the indoor units to continue operating using stored heat medium even when the heat-source device or relay unit experiences abnormalities, preventing system-wide stoppage and improving reliability.
Solution Approach 2:
The relay unit pre-cools or pre-heats the heat medium (water or anti-freezing fluid) in the intermediate heat exchanger before it reaches the indoor units. This preliminary action stores thermal energy in the heat medium, creating a buffer that enables indoor units to continue operation for a period even when the heat-source device stops due to detected abnormalities.
2Duration of action of stationary object
If heat medium is used as buffer, then stoppage of indoor units is delayed, but system complexity increases
Solution Approach 1:
A relay unit serving as an intermediary component is introduced between the heat-source device and indoor units. This relay unit contains an intermediate heat exchanger that acts as a buffer, storing thermal energy in heat medium (water or anti-freezing fluid). This intermediary structure enables the indoor units to continue operation using stored thermal energy even when the heat-source device stops, extending operation continuation time while adding only one intermediate component rather than complex distributed storage systems.
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 configuration allows for continued operation of indoor units, delaying their stoppage and maintaining temperature stability in air-conditioned spaces, even if an abnormality occurs in the heat-source device or relay unit, by utilizing the heat medium's thermal buffering capacity.
Implementation Method 1
at least one relay unit that exchanges heat between the refrigerant supplied from the heat-source device and a heat medium such as water or anti-freezing fluid different from the refrigerant in an intermediate heat exchanger
Implementation Method 2
at least one indoor unit that exchanges heat between the heat medium supplied from the relay unit and air of a region to be air-conditioned in a use side heat exchanger
Data Source
AI summary
An air-conditioning apparatus is provided with a heat-source device that supplies a refrigerant, a relay unit that exchanges heat of a heat medium such as water or anti-freezing fluid supplied from the heat-source device in an intermediate heat exchanger and supplies the heat medium, an indoor unit that exchanges heat between a use side heat exchanger through which the heat medium supplied from the relay unit flows and indoor air and performs cooling or heating in the indoor space, a controller that controls operations of the heat-source device, the relay unit and the indoor unit, and a third temperature sensor that detects the temperature of the heat medium flowing through the use side heat exchanger, and if an abnormality in at least one of the heat-source device and the relay unit is detected, the controller continues the operation of the indoor unit while the temperature detected by the third temperature sensor remains within a first predetermined temperature range.