Heat-Medium Air Conditioning Control for Leak-Safe Energy Saving
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing air-conditioning apparatuses for buildings face challenges such as refrigerant leakage, high energy consumption due to long heat medium circulation paths, complex construction requirements, and inefficiencies in refrigerant flow management, leading to increased costs and noise.
Innovation Solution
The air-conditioning apparatus incorporates a refrigerant cycle and a heat medium cycle with a heat medium flow control device, temperature sensors, and a controller to manage the flow rate and temperature of the heat medium, reducing the number of pipes and improving energy efficiency while preventing refrigerant leakage into indoor spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refrigerant is circulated to indoor units, then heating and cooling functions are achieved, but refrigerant leakage to indoor space occurs
Solution Approach 1:
The system is divided into two separate circulation loops: a refrigerant loop confined to the outdoor unit, and a heat medium loop that serves indoor units. This segmentation isolates the refrigerant to a safe location while maintaining heating/cooling functionality through the heat medium that interfaces with indoor units.
Solution Approach 2:
A heat medium (such as water or antifreeze solution) is introduced as an intermediary substance between the refrigerant and the indoor units. The refrigerant heats or cools the heat medium in the outdoor unit, and this heat-exchanged heat medium then circulates to indoor units, eliminating direct refrigerant exposure indoors while preserving thermal transfer functionality.
2Reliability
If heat medium circulation path is made long to avoid refrigerant in indoor units, then safety is improved, but energy consumption increases
Solution Approach 1:
The circulation system is segmented into an outdoor refrigerant loop and a separate heat medium loop. The heat medium loop is designed with optimized circulation paths that can be relatively long without excessive energy penalty because the heat medium operates at lower pressures and temperatures, reducing pumping power requirements compared to refrigerant circulation.
Solution Approach 2:
The system changes the physical parameters of the working fluid from refrigerant to heat medium, which has different thermodynamic properties. The heat medium operates with smaller temperature differentials and lower flow velocities, reducing the energy required for circulation even over longer paths, while still achieving effective heat transfer.
3Adaptability or versatility
If four pipes are arranged to allow free selection of cooling or heating, then versatility is improved, but ease of construction deteriorates
Solution Approach 1:
The heat medium circulation system is designed with multi-functional capability where the same heat medium pipes and heat exchangers can serve both heating and cooling modes. By controlling the direction of heat medium flow and the operation of the outdoor heat exchanger, the system provides both heating and cooling functions through a unified two-pipe configuration rather than requiring separate four-pipe systems.
4Ease of operation
If secondary medium circulating devices are provided to each indoor unit, then heating and cooling control is improved, but device complexity and noise increase
Solution Approach 1:
The control functions for multiple indoor units are merged into a single outdoor unit controller. The outdoor unit controller manages the refrigerant cycle and heat medium circulation centrally, coordinating the operation of all connected indoor units without requiring individual circulating devices or controllers at each indoor location, thereby reducing overall system complexity and noise.
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 reduces energy consumption, simplifies construction, and enhances safety by minimizing refrigerant exposure in indoor areas, while allowing for efficient heating and cooling operations with reduced noise and increased system efficiency.
Implementation Method 1
a heat exchanger related to heat medium which exchanges heat between the heat source side refrigerant and the heat medium
Implementation Method 2
pumps, the use side heat exchangers, and the heat exchangers related to heat medium connect to form a plurality of heat medium cycle circulating a heat medium
Implementation Method 3
a plurality of expansion devices... connect to form a refrigerant cycle circulating a heat source side refrigerant
Implementation Method 4
a compressor... connect to form a refrigerant cycle circulating a heat source side refrigerant
Data Source
AI summary
To provide an air-conditioning apparatus capable of achieving energy saving, a pump control of controlling the operating capacity of a pump is performed such that an opening degree of a heat medium flow control device, controlled by a heat-medium-flow-control-device control, approaches a target opening degree, and a refrigeration cycle of a refrigerant circuit is controlled such that the temperature of a heat medium, whose flow rate is controlled by the heat-medium-flow-control-device control and the pump control, approaches a target temperature.