Heat-Pump Chiller With Third Heat Exchanger for Multi-Mode Operation
Solution Overview
Problem
Existing HVAC&R systems face limitations in providing efficient and cost-effective heating and cooling solutions, particularly in large buildings, with issues such as fouling, limited control over water temperatures, high pressure drops, and environmental concerns related to refrigerant leaks, especially with flammable and toxic refrigerants.
Innovation Solution
A versatile HVAC&R system with a condenser, evaporator, and a third heat exchanger that can operate in multiple modes by controlling valving, minimizing field refrigerant piping, and using control circuitry to manage refrigerant flow and pressure drops, allowing for efficient heating and cooling with reduced refrigerant exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If water-to-water heat pumps are used for heating and cooling, then efficiency and control over hot water temperatures are improved, but the system requires simultaneous heating and cooling loads for proper operation and is prone to fouling when used with wet tower evaporators in cooling-only mode
Solution Approach 1:
The system is designed to perform multiple functions - it can operate as a cooling-only chiller, a heat pump providing both heating and cooling, or a chiller with heat recovery. The third heat exchanger and control system enable the same equipment to adapt to different operational requirements, eliminating the need for separate systems for different modes of operation.
2Ease of manufacture
If air-cooled chillers with heat recovery are used, then the system is inexpensive and efficient at high ambient temperatures, but control over water temperatures and available heating capacity are limited, particularly at lower ambient temperatures
Solution Approach 1:
The third heat exchanger acts as an intermediary component that enables precise control over water temperatures in both heating and cooling modes. By introducing this additional heat exchange surface, the system can modulate heat transfer more effectively than conventional air-cooled chillers, achieving better temperature control without sacrificing cost-effectiveness.
3Measurement precision
If air-to-water heat pumps are used for heating and cooling, then efficient heating and good control over water temperatures are achieved, but the system is expensive and does not provide heating and cooling in a single unit
Solution Approach 1:
The patent combines heating and cooling capabilities in a single integrated chiller system. By merging the cooling cycle with a third heat exchanger that can function as either a condenser or evaporator, the system provides both heating and cooling through one unit, eliminating the need for separate heat pump equipment and reducing overall system complexity.
4Productivity
If refrigerant is used in HVAC systems, then heating and cooling functions are achieved, but refrigerant can leak directly into occupied space creating environmental concerns, especially with flammable and toxic refrigerants
Solution Approach 1:
The system extracts and removes refrigerant from occupied spaces by configuring all refrigerant components (compressor, condenser, evaporator, expansion device) to be located outside the conditioned space. This separation eliminates the hazard of refrigerant leakage into occupied areas while maintaining heating and cooling efficiency through proper heat exchanger design.
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 system achieves efficient and cost-effective operation with improved control over water temperatures, reduced pressure drops, and enhanced safety by minimizing refrigerant exposure, offering a wide range of operational modes and energy savings.
Implementation Method 1
a condenser that condenses circulating refrigerant
Implementation Method 2
an evaporator that vaporizes the refrigerant
Implementation Method 3
A compressor compresses the vaporized refrigerant
Implementation Method 4
A further heat exchanger is coupled between the condenser and the evaporator, and receives the circulating refrigerant, and may either extract heat from the fluid, inject heat into the fluid
Data Source
Figure 1~3
Figure 2
Figure 4~5
AI summary
A heating and cooling system includes an evaporator (14), a compressor (16), and a condenser (12). A heat exchanger (18), which may be an outdoor heat exchanger, is configured to receive the refrigerant from the condenser, to selectively extract heat from or to add heat to the refrigerant, and to transfer the refrigerant to the evaporator. First control valving (34), disposed between the condenser and the heat exchanger, is configured to regulate flow of the refrigerant from the condenser to the heat exchanger in a first mode of operation. Second control valving (36), disposed between heat exchanger and the evaporatur, is configured to regulate flow of the refrigerant from the heat exchanger to the evaporator in a second mode of operation. The system may be operated in a variety of modes by appropriate control of the valving and other system components.