Dual-Cycle Heat Pump Using Undercooling Heat for Higher COP
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Solution Overview
Problem
Existing heat pumps face challenges in achieving high energy efficiency and flexibility, particularly in high heating/cooling power applications, with conventional two-stage systems often having low Coefficient of Performance (COP) and limited ability to handle diverse thermal user requirements.
Innovation Solution
A heat pump unit incorporating a secondary heat pump cycle that utilizes the undercooling heat power from the main cycle to enhance the overall useful heat power transfer, with a configuration that includes a main condenser, a first heat exchanger for undercooling, and a secondary evaporator and condenser to increase COP by minimizing electrical energy use and allowing flexible operation across various thermal gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a two-stage heat pump system is used to achieve high heating power, then the heating/cooling power is improved, but the COP deteriorates
Solution Approach 1:
The invention converts the harmful waste heat from undercooling the refrigerant in the condenser into a beneficial resource by directing it to preheat the heat carrier fluid in the hot water tank. This prevents energy waste and improves overall system efficiency, allowing the two-stage system to maintain high heating power while achieving COP ≥ 3.
2Temperature
If the condensation temperature is increased to 80-85°C for high temperature heating, then the heating temperature is improved, but the energy efficiency deteriorates
Solution Approach 1:
The system performs preliminary heating of the heat carrier fluid using waste heat from undercooling before the main heating phase. This preliminary action reduces the temperature lift required during main heating operation, allowing the system to maintain high condensation temperatures (80-85°C) while improving overall energy efficiency.
3Power
If the heat pump system is designed for high power output, then the heating/cooling capacity is improved, but the adaptability to different thermal users deteriorates
Solution Approach 1:
The invention implements dynamic control of the heat pump system with variable speed compressors and controllable heat exchangers that can adjust their operation based on real-time thermal demands. This allows a single high-power system to dynamically adapt to different thermal user requirements, providing flexible temperature and capacity control for multiple simultaneous users.
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 increases the overall COP by up to 20% compared to conventional systems, providing improved energy efficiency and flexibility, allowing the heat pump to effectively serve thermal users with different requirements and operating temperatures with reduced electrical compression power.
Implementation Method 1
a main condenser adapted to perform the condensation of the operating fluid of said main heat pump cycle
Implementation Method 2
a first heat exchanger, connected downstream of said main condenser and upstream of expansion means of said at least one main circuit, adapted to perform an undercooling of the operating fluid of said main heat pump cycle after the condensation of the same in said main condenser
Implementation Method 3
a secondary evaporator adapted to perform at least the evaporation of the operating fluid of said secondary heat pump cycle and in heat exchange relationship with said first heat exchanger to transfer heat power released by the operating fluid of said main heat pump cycle during said undercooling
Implementation Method 4
a secondary condenser adapted to perform the condensation of the operating fluid of said secondary heat pump cycle and intended to be connected to the external circuit of said first thermal user plant or to an external circuit of a second thermal user plant
Implementation Method 5
a main evaporator adapted to perform the evaporation of the operating fluid of said main heat pump cycle and intended to be connected to an external circuit of a heat sink
Data Source
Figure 1~2
Figure 1A
Figure 3
AI summary
A heat pump unit (1) comprises at least one main circuit (2) adapted to perform a main heat pump cycle with a respective operating fluid, which comprises: a main condenser (S4) adapted to perform the condensation of the operating fluid of the main heat pump cycle and intended to be connected to an external circuit of a first thermal user plant (10) in a heating operating mode of said heat pump unit (1 ), a first heat exchanger (S2), connected downstream of the main condenser (S4) and upstream of expansion means (L2) of said the main circuit (2), ), adapted to perform an undercooling of the operating fluid of the main heat pump cycle after the condensation of the same in the main condenser (S4), and a main evaporator (S8) adapted to perform the evaporation of the operating fluid of the main heat pump cycle and intended to be connected to an external circuit of a heat sink (20) in a heating operating mode of said heat pump unit (1). The heat pump unit (1) further comprises a secondary circuit (3) adapted to perform a secondary heat pump cycle with a respective operating fluid, which comprises: a secondary evaporator (S2) adapted to perform at least the evaporation of the operating fluid of the secondary heat pump cycle and in heat exchange relationship with the first heat exchanger (S2) to transfer heat power released by the operating fluid of the main heat pump cycle during said undercooling to the operating fluid of the secondary heat pump cycle, and a secondary condenser (S1 ) adapted to perform the condensation of the operating fluid of said secondary heat pump cycle (HPCS) and intended to be connected to the external circuit of the first thermal user plant (10) or to an external circuit of a second thermal user plant, different from the first thermal user plant (10).