Two-Stage Vehicle Cooling System with Intermediate Heat Exchanger
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Solution Overview
Problem
Existing refrigeration systems in vehicles face challenges with refrigerants that have high greenhouse potential or are flammable, posing safety and environmental concerns.
Innovation Solution
A two-stage refrigeration system with separate refrigerant circuits is implemented, where a non-flammable refrigerant with low greenhouse potential is used in the primary circuit outside the vehicle, and a safe, non-flammable refrigerant like a glycol alcohol is used in the secondary circuit inside the vehicle, with an intermediate heat exchanger for heat exchange, ensuring safety and environmental friendliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If refrigerants with high greenhouse potential (R134a, R404a) are used for deep-freezing in refrigeration machines, then cooling performance is achieved, but environmental harm increases due to high GWP values
Solution Approach 1:
The refrigeration system is divided into two separate circuits: a first refrigerant circuit containing the refrigeration machine with high-GWP refrigerant (R134a or R404a) for deep-freezing applications, and a second refrigerant circuit with low-GWP refrigerant (R1234yf or R1234ze) for climate control. This segmentation allows each circuit to use optimally suited refrigerants without compromising environmental performance or cooling effectiveness.
2Object-generated harmful factors
If flammable refrigerants (propane, HFO1234yf, HFO1234ze) are used to reduce greenhouse potential, then environmental friendliness improves, but safety risks increase due to flammability
Solution Approach 1:
The system separates flammable low-GWP refrigerants into a dedicated second refrigerant circuit that is spatially isolated from the passenger compartment through the intermediate heat exchanger arrangement. This allows use of environmentally friendly refrigerants while maintaining safety by preventing their presence inside the vehicle interior.
Solution Approach 2:
The intermediate heat exchanger serves as a mediator between the first refrigerant circuit (with high-GWP refrigerant) and the second refrigerant circuit (with low-GWP refrigerant), enabling heat exchange without direct contact between the two refrigerants. This intermediary device allows safe integration of flammable refrigerants into the system while maintaining environmental benefits.
3Device complexity
If a single refrigerant circuit is used throughout the vehicle, then system complexity is reduced, but safety and environmental performance cannot be optimized simultaneously
Solution Approach 1:
The refrigeration system is divided into two separate circuits: a first refrigerant circuit containing the refrigeration machine with high-GWP refrigerant (R134a or R404a) for deep-freezing applications, and a second refrigerant circuit with low-GWP refrigerant (R1234yf or R1234ze) for climate control. This segmentation allows each circuit to use optimally suited refrigerants without compromising environmental performance or cooling effectiveness.
Solution Approach 2:
The two separate refrigerant circuits are merged through the intermediate heat exchanger, which enables heat exchange between the circuits without direct refrigerant mixing. This merging approach allows the system to achieve the safety and environmental benefits of separate circuits while maintaining a integrated system architecture.
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 allows the use of refrigerants with low greenhouse potential without safety risks to passengers, as potentially hazardous refrigerants are contained outside the passenger area, and safer alternatives are used inside, enhancing both safety and environmental sustainability.
Implementation Method 1
at least one intermediate heat exchanger for heat exchange between the first refrigerant circuit and the second refrigerant circuit
Data Source
Figure 1
AI summary
The invention relates to a spacious vehicle having at least one under-floor cooling unit (1) having a first coolant circuit (2), wherein a second coolant circuit (10) extends at least partially inside the vehicle and an intermediate heat exchanger (6) is provided for heat exchange between the first coolant circuit (2) and the second coolant circuit (10).