Outdoor Heat Pump Unit With Three-Pipe Heat-Recovery Dehumidification
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Solution Overview
Problem
Existing variable-frequency multi-connected heat pump systems are complex and costly to control due to the need for multiple four-way valves to recover heat, which can lead to poor dehumidification performance in rainy or low-temperature environments, affecting thermal comfort.
Innovation Solution
A heat recovery variable-frequency multi-connected heat pump system utilizing a four-way valve, high-pressure and low-pressure gas pipes, and two sets of electronic expansion valves and heat exchangers, allowing for six operating conditions that enable efficient heat recovery, dehumidification, and improved thermal comfort by using a three-pipe design with a four-way valve and two sets of electronic expansion valves and heat exchangers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple four-way valves are used to recover heat in the system, then heat recovery capability is improved, but device complexity and control cost increase
Solution Approach 1:
The patent merges the functions of multiple four-way valves into a single four-way valve by redesigning the refrigerant pipe connections. The high-pressure gas pipe and low-pressure gas return pipe are directly connected to the four-way valve, eliminating the need for additional valves while maintaining heat recovery capability through optimized refrigerant flow paths.
Solution Approach 2:
The single four-way valve in the patent is designed to perform multiple functions: it controls refrigerant flow for both heating and cooling modes, and enables heat recovery operations without requiring separate dedicated valves. This multi-functional design reduces the total number of components while preserving all necessary operational capabilities.
2Reliability
If the system refrigerates for temperature lowering and dehumidification in low-temperature environments, then dehumidification effect is improved, but thermal comfort deteriorates due to low outgoing air temperature
Solution Approach 1:
The patent changes the operational parameters by introducing a bypass path through the high-pressure gas pipe that allows a portion of the high-pressure refrigerant gas to mix with the outgoing air. This parameter change enables the system to maintain dehumidification performance while raising the temperature of outgoing air to improve thermal comfort.
Solution Approach 2:
The high-pressure gas pipe acts as an intermediary element that facilitates heat transfer from the high-pressure refrigerant gas to the outgoing air stream. This intermediary mechanism allows thermal energy to be transferred without requiring direct contact between the refrigerant and the air, thereby improving outgoing air temperature while maintaining dehumidification effectiveness.
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 system improves thermal comfort and efficiency by allowing any indoor unit to operate for refrigeration, heating, or heat recovery and dehumidification, enhancing the system's refrigeration and heating capacity while simplifying control through a reduced number of valves and expanded operational conditions.
Implementation Method 1
an exhaust end of the compressor (1) is connected with an A end of the four-way valve (4)
Implementation Method 2
a four-way valve (4), an outdoor heat exchanger (5), an outdoor electronic expansion valve (6)
Implementation Method 3
another end of the outdoor heat exchanger (5) is connected with the high-pressure liquid pipe through the outdoor electronic expansion valve (6)
Implementation Method 4
a four-way valve (4), an outdoor heat exchanger (5), an outdoor electronic expansion valve (6)
Data Source
AI summary
A heat recovery variable-frequency multi-split heat pump system and a control method thereof. The system includes an outdoor unit and at least two indoor units. The system is a three-pipe heating recovery multi-split heat pump system designed on the basis of a four-way reversing valve, and one indoor unit thereof is provided with two electronic expansion valves and two heat exchangers so that any indoor unit in the system can operate independently under three working conditions of refrigeration, heating or heat recovery dehumidification. Under multi-split condition, the system can operate under six working conditions, namely, the full-refrigeration working condition, the full-heating working condition, the common-heat-recovery working condition, the common-heat-recovery-dehumidification working condition, the heat recovery dehumidification-refrigeration-combination working condition and the heat recovery dehumidification-heating-combination working condition. Under the heat recovery dehumidification condition, a lower outlet air temperature, during low-temperature dehumidification, is raised by means of heat removal of a condenser so as to achieve the purpose of dehumidification without temperature fall or temperature rise, so that the thermal comfort and efficiency of the system are improved, and the refrigerating capacity and heating capacity of the system are effectively improved.