Air Conditioner Three-Cycle Defrosting Using Water-Side Heat Recovery
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Solution Overview
Problem
Conventional air conditioning systems are unable to effectively increase defrosting capacity during heating-only operations, leading to prolonged defrosting times and reduced efficiency, as they rely solely on electricity and cooling load heat for defrosting, neglecting the potential of the water-side cycle.
Innovation Solution
The system incorporates a three-cycle configuration, utilizing both a compressor and a second medium as heat sources, with flow path switching valves to redirect heat exchange paths, allowing the second medium to enhance defrosting capacity during heating-only operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional defrosting operation is performed using only compressor electricity and cooling load heat during heating-only operation, then the system structure remains simple, but the defrosting capacity is insufficient and defrosting time is prolonged
Solution Approach 1:
The patent merges the water-side cycle (secondary cycle) with the refrigerant-side cycle (primary cycle) to create a unified defrosting system. The second heat exchanger serves dual purposes: heat exchange during normal operation and defrosting heat source during defrosting operation. This integration allows the system to combine compressor electricity, cooling load heat, and water-side cycle heat into a single powerful defrosting mechanism, significantly increasing defrosting capacity without proportionally increasing system complexity
Solution Approach 2:
The patent makes the water-side cycle (secondary cycle) multi-functional by enabling it to serve both normal heating/cooling operations and defrosting operations. The second heat exchanger and water circulation system are designed to function in multiple modes: heat exchange during normal operation and defrosting heat source during defrosting operation. This universality allows the existing water-side infrastructure to contribute to defrosting capacity without requiring entirely separate dedicated defrosting equipment
2Loss of time
If the water-side cycle is utilized as a heat source for defrosting, then defrosting capacity increases and defrosting time shortens, but the system complexity increases due to additional flow path switching components
Solution Approach 1:
The patent implements dynamic flow path switching using four-way valves and flow rate adjusting valves that can adaptively redirect fluid flow based on operational requirements. During defrosting operation, these valves dynamically switch the water-side cycle connection from the heat exchanger to the second heat exchanger, and adjust flow rates to optimize heat delivery to the frost-covered surfaces. This dynamic capability enables rapid defrosting while managing system complexity through intelligent control of existing components
Solution Approach 2:
The patent introduces flow rate adjusting valves as intermediary components that mediate between the water-side cycle and the defrosting process. These valves serve as controllable intermediaries that regulate and direct the flow of water or secondary refrigerant to the second heat exchanger during defrosting operation. By using these intermediary flow control devices, the system can efficiently manage the transition to defrosting mode and optimize heat transfer without requiring complete system redesign
3Use of energy by moving object
If only compressor electricity is used for defrosting, then the system operation is simple, but the defrosting capacity is limited and energy efficiency is reduced
Solution Approach 1:
The patent recovers and utilizes waste heat from the water-side cycle (secondary cycle) that would otherwise be discarded during heating-only operation. Instead of allowing this thermal energy to be lost, the system redirects it through the second heat exchanger to the frost-covered air heat exchanger. This recovery of otherwise wasted heat energy significantly boosts defrosting capacity and improves overall energy efficiency without requiring additional primary energy sources
Solution Approach 2:
The patent changes the operational parameters of the water-side cycle by adjusting flow rates and redirecting flow paths during defrosting operation. The flow rate adjusting valves modify the flow characteristics of water or secondary refrigerant to optimize heat transfer efficiency to the second heat exchanger. This parameter adjustment enables the system to dynamically adapt the water-side cycle for defrosting purposes, maximizing energy utilization from available heat sources
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 significantly reduces defrosting time and improves operational efficiency by leveraging the second medium as a heat source, effectively addressing the limitations of conventional systems.
Implementation Method 1
a second heat exchanger that exchanges heat between the first cycle and the second cycle
Implementation Method 2
exchanges heat between the first cycle and the second cycle
Implementation Method 3
a compressor
Implementation Method 4
a second pump that drives the second medium
Data Source
Figure 1
Figure 2
Figure 3
AI summary
There are provided: a first cycle 5, in which a first medium is circulated, the first cycle having a compressor 9, a first heat exchanger 11 structured with an air heat exchanger, a second heat exchanger 15, and a third heat exchanger 17; a second cycle 6, in which a second medium is circulated and heat is exchanged with the first medium through the second heat exchanger 15, the second cycle having indoor units 34a to 34c, each having a fan; a third cycle 7, in which the second medium is circulated and heat is exchanged with the first medium through the third heat exchanger 17, the third cycle sharing the indoor units with the second cycle 6; and flow path switching valves 31a to 31c and 37a to 37c that switch flow paths between the second cycle and third cycle. Before the first heat exchanger 11 is defrosted, a halted indoor unit is filled with the second medium in the third cycle 7 with its fan being halted. The third heat exchanger 17 functions as an evaporator during defrosting operation.