Parallel Indoor Heat Exchanger Switching for Faster Heat Pump Warm-Up
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Solution Overview
Problem
In heat pump type air-conditioning apparatuses, stopping the indoor fan during heating startup leads to refrigerant stagnation in the second heat exchanger, delaying the increase in high-pressure-side pressure and extending the time before warm air is supplied to the indoor space.
Innovation Solution
The air-conditioning apparatus employs three-way and four-way valves to control refrigerant flow, blocking the second load-side heat exchanger from the refrigerant path during startup, reducing the heat transfer area and preventing refrigerant stagnation, thereby accelerating the increase in condensing temperature and high-pressure-side pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the indoor fan is stopped during heating startup to prevent cold air blowout, then cold air supply is prevented, but refrigerant stagnation occurs in the second heat exchanger delaying pressure increase and extending warm air supply time
Solution Approach 1:
The load-side heat exchanger is divided into a first heat exchanger and a second heat exchanger connected in parallel. During heating startup, the refrigerant flow to the second heat exchanger is blocked while the first heat exchanger operates normally, preventing refrigerant stagnation in the second heat exchanger while still providing heating capacity through the first heat exchanger.
Solution Approach 2:
Before the heating operation fully starts, the refrigerant flow path to the second heat exchanger is blocked in advance to prevent refrigerant stagnation. This preliminary action ensures that the refrigerant can quickly increase pressure and temperature in the first heat exchanger, enabling faster warm air supply when the indoor fan restarts.
2Area of stationary object
If refrigerant flow path includes all heat exchangers, then heat transfer area is maximized, but refrigerant stagnation occurs reducing condensing temperature increase rate
Solution Approach 1:
The load-side heat exchanger is segmented into first and second heat exchangers in parallel configuration. During heating startup, only the first heat exchanger receives refrigerant flow, effectively reducing the active heat transfer area to prevent refrigerant stagnation and accelerate condensing temperature increase.
Solution Approach 2:
The refrigerant flow path is dynamically controlled using flow blocking means to adjust which heat exchangers receive refrigerant based on operating conditions. During heating startup, the second heat exchanger is blocked while the first operates; during cooling operation, both heat exchangers operate in parallel, optimizing performance for each mode.
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 the time from heating startup to warm air supply by quickly increasing the condensing temperature and high-pressure-side pressure, enhancing heating performance and capacity.
Implementation Method 1
The air-conditioning apparatus employs three-way and four-way valves to control refrigerant flow, blocking the second load-side heat exchanger from the refrigerant path during startup
Implementation Method 2
a first load-side heat exchanger 12a and a second load-side heat exchanger 12b which are connected in parallel with each other
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An air-conditioning apparatus includes a refrigerant circuit including a first load-side heat exchanger and a second load-side heat exchanger, a first flow switching unit located upstream of the second load-side heat exchanger, and a second flow switching unit located downstream of the second load-side heat exchanger, wherein the first flow switching unit is configured to be switched between a first state in which refrigerant communication between a compressor and the second load-side heat exchanger is blocked and a second state in which the compressor is in refrigerant communication with the first load-side heat exchanger and the second load-side heat exchanger, and the second flow switching unit is configured to be switched between a third state in which refrigerant communication between the second load-side heat exchanger and a heat-source-side heat exchanger is blocked and a fourth state in which the first load-side heat exchanger is in refrigerant communication with the second load-side heat exchanger and the heat-source-side heat exchanger.