Spa Heat Pump System with Integrated Water Side Heat Exchanger
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Solution Overview
Problem
Existing heating units for spas and hot tubs face inefficiencies and are not suited for the harsh chemical and temperature environments, with known electrical heaters being too large, inefficient, and requiring substantial time to heat water to desired temperatures.
Innovation Solution
A compact heat pump system integrated into the spa or hot tub, comprising a water side and air side heat exchanger, a compressor, and refrigerant conduits, along with a controller and temperature sensor, which uses a combination of electric heating to quickly raise water temperature, while being corrosion-resistant and efficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a heat pump system is used to heat spa water, then energy efficiency is improved, but the system becomes too large and bulky for compact spa installations
Solution Approach 1:
The heat pump system components are nested within the spa structure itself. The heat exchanger is positioned inside the spa tub, utilizing the available space efficiently. The compressor and control components are integrated into the spa's existing housing structure, creating a compact configuration that fits within standard spa dimensions.
Solution Approach 2:
The heat exchanger uses a vertical orientation with refrigerant flowing through vertically arranged tubes, maximizing heat transfer surface area within a compact footprint. This vertical arrangement allows the heat exchanger to provide efficient heating without requiring excessive horizontal space.
2Temperature
If known heat pumps are used for swimming pools, then heating capability is provided, but they cannot heat water to higher temperatures required for spas
Solution Approach 1:
The heat pump system is specifically designed with parameters optimized for spa applications. The heat exchanger is configured to deliver higher temperatures (up to 140°F) compared to pool heat pumps. The refrigerant flow rates, compressor capacity, and heat exchanger surface areas are all parameterized to match the higher temperature requirements of spa water heating.
3Power
If electrical resistance heating is used, then heating function is provided, but the harsh chemical and temperature environment creates corrosive conditions
Solution Approach 1:
The heat pump system uses refrigerant as an intermediary heat transfer medium instead of direct electrical resistance heating. The refrigerant circulates through sealed tubes in the heat exchanger, transferring heat to the spa water without direct contact between electrical elements and the corrosive water environment. This intermediary approach eliminates corrosion issues while maintaining heating effectiveness.
Solution Approach 2:
The heat exchanger components are constructed from corrosion-resistant materials such as stainless steel or chemically resistant polymers. These composite or specialized materials are selected specifically to withstand the harsh chemical environment of spa water, including exposure to chlorine, bromine, and temperature extremes.
4Loss of time
If electrical heaters with limited power are used, then heating function is provided, but substantial time is required to heat water to desired temperature
Solution Approach 1:
The heat pump utilizes phase transitions of the refrigerant (evaporation and condensation) to transfer heat efficiently. During evaporation, the refrigerant absorbs heat from the spa water; during condensation, it releases heat to the water. This phase change mechanism enables rapid heat transfer at higher power levels compared to simple electrical resistance heating, significantly reducing the time required to heat water to desired temperatures.
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 efficiently maintains water temperatures between 45° F to 140° F, providing rapid heating and cooling, conserving energy by allowing the system to be turned off during non-use, and is durable in harsh environments.
Implementation Method 1
a heat pump system including a water side heat exchanger and an air side heat exchanger
Implementation Method 2
refrigerant conduits fluidly interconnecting the water side heat exchanger and the air side heat exchanger to the compressor, and providing for flow of refrigerant through the water side heat exchanger and through the air side heat exchanger when compressed by the compressor
Implementation Method 3
a compressor, and refrigerant conduits fluidly interconnecting the water side heat exchanger and the air side heat exchanger to the compressor, and providing for flow of refrigerant through the water side heat exchanger and through the air side heat exchanger when compressed by the compressor
Implementation Method 4
a water pump and a plurality of fluid conduits fluidly interconnecting the pump to the water side heat exchanger and the fluid inlets and fluid outlet, such that the water pump circulates water from the tub cavity through the water side heat exchanger
Implementation Method 5
One type of known heater utilizes an electrical resistance element that generates heat when electrical current passes through the electrical resistance element
Data Source
AI summary
A spa or hot tub system includes a tub forming a cavity that holds a fluid such as water therein, and a water circulation system provides for circulation of water within the tub. The hot tub includes inner and outer surfaces, and defines an internal space. A heat pump system is operably connected to the water circulation system, and heats the water in the hot tub. The water side heat exchangers of the heat pump may include a polymer housing, and coiled inner elements for refrigerant. The coils may be made of a corrosion-resistant metal tubing or the like. The system may include a conventional electric heating element in addition to the heat pump to provide additional heating capacity.