Method and system for operating a refrigeration system with a heat pump function and a regeneration function for heat sources and a motor vehicle including such a system
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Solution Overview
Problem
Refrigeration systems with heat pump functions in motor vehicles face challenges in maintaining efficient heating output due to excessive cooling of heat sources, leading to reduced performance and increased energy consumption.
Innovation Solution
A method is proposed that involves monitoring the coolant temperature and adjusting the expansion valves to route the refrigerant mass flow through a third heat exchanger only when the coolant temperature is above a certain threshold, thereby preventing excessive cooling. Additionally, switching on a secondary heat source, such as ambient air, helps maintain the coolant temperature and balance the heating output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the refrigerant extracts heat from the coolant in the third heat exchanger, then the heating output is improved, but the coolant temperature decreases excessively leading to reduced performance
Solution Approach 1:
The control unit continuously monitors the coolant temperature and adjusts the expansion valve position accordingly. When the coolant temperature approaches the lower limiting value, the control unit reduces the refrigerant mass flow through the third heat exchanger by adjusting the expansion valve, thereby preventing excessive cooling while maintaining optimal heating output.
Solution Approach 2:
The system dynamically adjusts the refrigerant mass flow through the third heat exchanger based on real-time coolant temperature conditions. The expansion valve is controlled to vary the refrigerant flow rate, enabling the system to adapt to changing thermal conditions and maintain stable operation within the optimal temperature range.
2Power
If the refrigerant mass flow through the third heat exchanger is increased, then the heating performance is improved, but the energy consumption increases
Solution Approach 1:
The system optimizes energy consumption by dynamically changing the refrigerant mass flow parameter through expansion valve control. By adjusting the expansion valve position based on coolant temperature feedback, the system maintains the refrigerant flow at optimal levels that maximize heating performance while minimizing unnecessary energy consumption.
3Loss of energy
If the coolant temperature is allowed to drop below the lower limiting temperature, then the heat extraction efficiency is improved, but the coolant volume flow collapses
Solution Approach 1:
The control unit takes preliminary action by monitoring the coolant temperature and adjusting the expansion valve before the coolant temperature drops to the lower limiting temperature. This preventive control prevents the coolant temperature from reaching levels that would cause volume flow collapse, thereby maintaining both heat extraction efficiency and system reliability.
Solution Approach 2:
The system uses feedback control by continuously monitoring coolant temperature and adjusting the refrigerant mass flow through the expansion valve. When the coolant temperature approaches the lower limiting value, the feedback mechanism reduces the refrigerant flow to prevent excessive cooling that would lead to coolant volume flow collapse.
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 method optimizes energy consumption by preventing excessive cooling of the coolant, ensuring stable heating output, and reducing the risk of coolant volume flow collapse, thereby enhancing the overall performance of the refrigeration system.
Implementation Method 1
a total mass flow of refrigerant flows through the third heat exchanger and is evaporated in the third heat exchanger by waste heat from coolant circulating in the third heat exchanger
Implementation Method 2
is evaporated in the third heat exchanger by waste heat from coolant circulating in the third heat exchanger
Implementation Method 3
a refrigerant compressor which is connectable or connected to a primary line and a secondary line
Data Source
AI summary
A method for operating a refrigeration system having a heat pump function for motor vehicle, including the following steps: setting a heat pump operation, in which the refrigerant is routed from the refrigerant compressor into the secondary line; setting an expansion valve assigned to the third heat exchanger such that a total mass flow of refrigerant flows through the third heat exchanger; and detecting the temperature of the coolant in the third heat exchanger. The total mass flow of refrigerant is routed through the third heat exchanger when the temperature of the coolant is greater than an upper limiting temperature.