Refrigeration cycle device
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Solution Overview
Problem
Existing refrigeration cycle systems face challenges in preventing temperature decreases of heat media like water or brine due to overlapping defrosting periods of multiple heat pumps, which can be exacerbated by variations in load and delayed defrosting.
Innovation Solution
A refrigeration cycle apparatus with two independent refrigeration cycle units connected in a common circulation path, featuring a control device that adjusts heating and defrosting capacities to prevent overlapping defrosting periods by determining the defrosting capacity based on load and inter-unit intervals, ensuring the defrosting capacity does not exceed the heating capacity of the other unit and maintaining a balanced heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If defrosting operation is performed for multiple heat pumps independently, then each heat pump can maintain its heat exchanger, but the water temperature decreases due to overlapping defrosting periods
Solution Approach 1:
The control device merges the control of multiple heat pumps into a unified system that coordinates defrosting operations. By treating the plurality of heat pumps as an integrated system rather than independent units, the controller can schedule defrosting to avoid overlaps, thereby maintaining water temperature while still performing necessary defrosting maintenance on each heat exchanger.
Solution Approach 2:
The control device performs preliminary scheduling of defrosting operations by predicting future defrosting needs and coordinating them in advance. By calculating expected defrosting periods and water temperature trends beforehand, the system can adjust operation timing to prevent overlapping defrosting that would cause excessive water temperature decrease.
2Temperature
If defrosting start time is delayed to avoid overlapping, then water temperature can be maintained, but heat pump capacity is lowered
Solution Approach 1:
The control device dynamically adjusts the defrosting start timing based on real-time water temperature measurements and predicted load variations. Rather than using fixed delayed scheduling, the system continuously adapts defrosting timing to current operating conditions, allowing heat pumps to operate at full capacity when water temperature permits while preventing excessive temperature drops when loads vary.
3Loss of time
If defrosting capacity is increased to clear frost faster, then defrosting period is shortened, but water temperature decreases more due to reduced heating capacity
Solution Approach 1:
The control device changes operational parameters by adjusting defrosting capacity based on water temperature conditions and load predictions. When water temperature is stable and load is predictable, the system can increase defrosting capacity to shorten defrosting time. When water temperature is low or load variations are expected, the system reduces defrosting capacity to maintain heating contribution, thereby optimizing the balance between defrosting efficiency and water temperature maintenance.
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 effectively suppresses temperature decreases of the heat medium while avoiding overlapping defrosting periods, ensuring stable water temperature and efficient heat transfer.
Implementation Method 1
a first refrigeration cycle unit 201 and a second refrigeration cycle unit 202 disposed in a common circulation path for a heat medium... each of the first refrigeration cycle unit 201 and the second refrigeration cycle unit 202 being configured to control temperature of the heat medium
Implementation Method 2
each of the first refrigeration cycle unit 201 and the second refrigeration cycle unit 202 having an independent refrigerant circuit using refrigerant
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
A control device (100) controls a heating capacity during a heating operation and a defrosting capacity during a defrosting operation. When a first defrosting start condition is satisfied, the control device (100) determines the defrosting capacity in the defrosting operation of a first refrigeration cycle unit (201), and starts the defrosting operation. The defrosting capacity of the first refrigeration cycle unit (201) is determined to fall within a range satisfying a first determination condition and within a range satisfying a second determination condition. The first determination condition is a condition that a sum of a load capacity of a load device (3) when the first defrosting start condition is satisfied, and the defrosting capacity of the first refrigeration cycle unit (201) does not exceed the heating capacity of a second refrigeration cycle unit (202). The second determination condition is a condition that a sum of an inter-unit defrosting interval and a defrosting period of the first refrigeration cycle unit (201) does not exceed a shortest defrosting interval of the second refrigeration cycle unit (202).