Heat Medium Storage Circuit for Faster HVAC Mode Switching
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Solution Overview
Problem
Existing air-conditioning systems for office buildings face challenges in quickly restarting operations, switching between heating and cooling, and executing freezing mode due to the time required to heat or cool large volumes of heat medium, leading to high energy consumption and complex construction needs.
Innovation Solution
An air-conditioning apparatus with a refrigerant circuit and a heat medium circuit that includes intermediate heat exchangers, a pump, and a heat medium energy storage system, where the heat-source-side refrigerant is used to store and transfer heating or cooling energy to the heat medium, reducing the time needed for these operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large volume of heat medium is used to serve multiple indoor units, then the system can meet the cooling or heating demands of multiple zones, but the time required to heat or cool the heat medium before operation increases significantly
Solution Approach 1:
The patent divides the heat medium circulation system into multiple independent circuits, with each circuit serving a specific indoor unit or group of units. This segmentation allows each heat medium circuit to be heated or cooled independently and in parallel, significantly reducing the total time required to prepare heat medium for multiple zones compared to a single large-volume system.
2Reliability
If the heat medium is heated or cooled by the heat-source-side refrigerant before being transported to indoor units, then the indoor units can operate effectively, but the energy consumption increases due to the time and power required for heating/cooling the heat medium
Solution Approach 1:
The system performs preliminary heating or cooling of the heat medium in the heat medium storage tank during periods when cooling or heating demand is low, such as during cooling operation when excess cooling capacity is available or during heating operation when excess heating capacity is available. This preliminary action stores thermal energy in the heat medium, which can then be quickly deployed when needed, reducing both the time and energy required for operational startup.
3Adaptability or versatility
If four water pipes are used to connect the heat source unit and indoor units for heat-recovery chiller operation, then cooling or heating can be freely selected on indoor units, but the construction complexity and cost increase
Solution Approach 1:
The patent implements a dual-purpose heat medium circulation system where the same heat medium circuits and pumps can operate in either heating mode or cooling mode by controlling the direction of heat transfer at the heat source unit. The heat medium serves both as a cooling carrier and a heating carrier, eliminating the need for separate four-pipe systems while maintaining the ability to freely select heating or cooling at each indoor unit.
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 reduces the time required for restarting, switching between heating and cooling, and executing freezing mode operations, while also minimizing energy consumption and simplifying construction by using a more efficient energy transfer mechanism.
Implementation Method 1
a heat source unit (an outdoor unit) is provided on the outside of a building, and indoor units are provided on the inside of the building. In such an air-conditioning apparatus, a refrigerant that circulates through a refrigerant circuit transfers its heat to (or receive heat from) air that is supplied to a heat exchanger included in each of the indoor units
Implementation Method 2
a heat medium energy storage that is connected to the heat medium circuit and stores the heat medium; and an intra-storage heat exchanger that is connected to the refrigerant circuit and heats or cools the heat medium in the heat medium energy storage
Data Source
AI summary
An air-conditioning apparatus includes a refrigerant circuit including a compressor, a first refrigerant flow switching device, a plurality of intermediate heat exchangers, a first expansion device, and a heat-source-side heat exchanger, through all of which a refrigerant circulates and all of which in combination form a refrigeration cycle; and a heat medium circuit including the plurality of intermediate heat exchangers, a pump, and a plurality of use-side heat exchangers, through all of which a heat medium circulates. The air-conditioning apparatus further includes a heat medium energy storage that is connected to the heat medium circuit and stores the heat medium; and an intra-storage heat exchanger that is connected to the refrigerant circuit and heats or cools the heat medium in the heat medium energy storage by using the heat-source-side refrigerant supplied thereto.