Method for exchanging heat in vapor compression heat transfer systems and vapor compression heat transfer systems comprising intermediate heat exchangers with dual-row evaporators or condensers
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Solution Overview
Problem
Existing vapor compression heat transfer systems, particularly those using fluoroolefins, face limitations in improving cooling capacity and energy efficiency, as they struggle to effectively utilize new working fluids like 2,3,3,3-tetrafluoropropene (HFC-1234yf) compared to traditional fluids like 1,1,1,2-tetrafluoroethane (HFC-124a).
Innovation Solution
Incorporating an internal heat exchanger that sub-cools the working fluid by circulating it through a system involving multiple heat exchange steps, including an intermediate heat exchanger and dual-row condensers or evaporators, to enhance the refrigeration capacity and energy efficiency of the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional vapor compression systems use conventional working fluids like HFC-124a, then system operation is simple, but cooling capacity and energy efficiency are limited
Solution Approach 1:
The condenser is divided into two separate circuits: a first circuit for condensing compressed refrigerant gas, and a second circuit for subcooling the condensed liquid refrigerant. This segmentation allows independent optimization of condensation and subcooling processes, enabling significant cooling capacity improvement while maintaining manageable system complexity
Solution Approach 2:
A heat exchanger is introduced as an intermediate component between the condenser and expansion device, forming an intermediate circuit that enables subcooling of the condensed refrigerant. This intermediary component facilitates heat transfer from the first circuit to the second circuit, achieving the desired temperature reduction and improving system performance
2Use of energy by moving object
If new working fluids like HFC-1234yf are used, then energy efficiency can be improved, but the system struggles to effectively utilize these fluids without additional components
Solution Approach 1:
The system performs subcooling of the refrigerant before it enters the expansion device, preparing the refrigerant in advance for more efficient evaporation and heat absorption. This preliminary action of reducing refrigerant temperature below its condensation point maximizes the energy efficiency potential of new working fluids like HFC-1234yf
Solution Approach 2:
The invention changes the temperature parameter of the condensed refrigerant by implementing subcooling, reducing it from saturation temperature to a lower temperature. This parameter change enables new working fluids to operate at optimal conditions, significantly improving energy efficiency and coefficient of performance
3Productivity
If subcooling is implemented to increase cooling capacity, then refrigeration capacity improves, but system complexity increases
Solution Approach 1:
The patent merges the subcooling function with the existing condenser system by using the condenser as the heat source for subcooling. The heat exchanger integrates the subcooling circuit with the condensation circuit, allowing both functions to operate simultaneously without requiring completely separate systems, thus improving refrigeration capacity while limiting complexity increase
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
The method significantly increases the coefficient of performance (COP) and cooling capacity of vapor compression heat transfer systems using fluoroolefins, such as HFC-1234yf, by up to 7.67% and 7.50% respectively, compared to systems without this configuration, while also improving energy efficiency.
Implementation Method 1
transferring heat from the liquid working fluid to the gaseous working fluid
Implementation Method 2
sub-cooling of the working fluid exiting out of the condenser... cooling a vapor below the saturation point
Data Source
AI summary
A multi-step method is disclosed for exchanging heat in a vapor compression heat transfer system having a working fluid circulating therethrough. The method includes the step of circulating a working fluid comprising a fluoroolefin to an inlet of a first tube of an internal heat exchanger, through the internal heat exchanger and to an outlet thereof. Also disclosed are vapor compression heat transfer systems for exchanging heat. The systems include an evaporator, a compressor, a dual-row condenser and an intermediate heat exchanger having a first tube and a second tube. A disclosed system involves a dual-row condenser connected to the first and second intermediate heat exchanger tubes. Another disclosed system involves a dual-row evaporator connected to the first and second intermediate heat exchanger tubes.