Solar Heat Recovery Loop for Low-Waste-Heat Water Heating
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Solution Overview
Problem
Conventional systems for heating water, such as heat recovery units and solar energy systems, face inefficiencies due to reduced waste heat availability in modern air conditioning and heat pump systems, and high costs associated with pumping water long distances for solar heating, respectively.
Innovation Solution
A solar hot water recovery system that combines a solar energy loop with a refrigerant loop to heat water, using cross-heat exchangers within a heat recovery unit to transfer heat from the refrigerant to the water, allowing for continuous solar heating even when the air conditioning or heat pump system is not running, and reducing electricity consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional heat recovery units are used to capture waste heat from air conditioning systems, then waste heat can be transferred to water, but the efficiency has declined due to reduced waste heat availability from improved AC systems
Solution Approach 1:
The patent combines a solar thermal system with a heat recovery unit (HRU) to create a hybrid system. The solar collectors provide additional heat input to the HRU, merging two heat sources (waste heat from AC and solar thermal energy) into a single water heating system. This resolves the contradiction by compensating for reduced waste heat availability through solar supplementation.
Solution Approach 2:
The heat recovery unit is designed to serve multiple functions: it captures waste heat from the AC system when operating, and simultaneously functions as a solar thermal heat exchanger when solar energy is available. The system can operate in different modes depending on AC operation status and solar availability, making it universally applicable regardless of AC system efficiency improvements.
2Use of energy by moving object
If solar panels are roof-mounted and water is heated by pumping water through heat exchangers, then solar energy can be used to heat water, but the cost increases due to pumps and multiple collectors
Solution Approach 1:
The patent merges the solar thermal collection function with the heat recovery unit's heat exchanger into a single integrated component. Instead of separate solar collectors and heat exchangers, the HRU housing contains both functions, reducing the number of components and simplifying the system architecture.
Solution Approach 2:
The heat transfer fluid circulating through the solar collectors and HRU acts as an intermediary medium. Rather than pumping water directly from the tank to solar collectors and back, a closed-loop heat transfer fluid carries thermal energy between the solar collectors and the water tank, reducing pump requirements and system complexity.
3Use of energy by moving object
If water is pumped long distances from ground level or building structure to roof-mounted solar panels, then solar heating can be achieved, but energy consumption increases due to pumping requirements
Solution Approach 1:
The system uses a heat transfer fluid as an intermediary that circulates through solar collectors on the roof and transfers heat to water in the tank through the HRU. This eliminates the need to pump water itself to the roof, as the lightweight heat transfer fluid can be circulated with minimal pumping energy, and heat is then transferred to the water in place.
Solution Approach 2:
The patent replaces the mechanical system of pumping water vertically to roof level with a thermal field-based solution. Heat transfer fluid circulation and thermal conduction/substitution eliminate the need for high-energy water pumping, using thermal energy transfer instead of mechanical water displacement.
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 at least double the efficiency of conventional heat recovery units in transferring heat to the water source, allowing for faster heating and reducing electricity consumption, while maintaining performance and effectiveness across various operating conditions.
Implementation Method 1
Cross-heat exchange takes place within the first heat exchanger between the heat transfer medium of the solar loop and the refrigerant medium of the refrigerant loop in order to produce a superheated refrigerant stream
Implementation Method 2
Cross-heat exchange takes place within the second heat exchanger between this still hot heat transfer medium and to-be-heated water stream in order to produce a heated hot water stream
Implementation Method 3
a solar panel in communication with the solar loop, the solar panel being in communication with a second heat exchanger of the heat recovery unit
Data Source
AI summary
A system of capturing waste heat includes a heat recovery unit (20) having a heat exchanger (35) arranged to transfer heat between a fluid circulating in a refrigerant loop (60) and a fluid circulating in a solar loop (70) and another heat exchanger (39) arranged to transfer heat between the fluid in the solar loop (70) and a fluid circulating in a water loop (50). Controllable first, second, and third three-way valves (V1-V3) provide or prevent, depending on fluid temperatures, an A-B, B-C, and A-C flow path through the valve. The first valve (V1) is arranged in the water loop (50) upstream of the second heat exchanger (39). The second (V2) is arranged in the solar loop (70) upstream of the second heat exchanger (39). The third valve (V3) is arranged in the solar loop (70) between the first and second heat exchangers (35, 39).