Cold climate heat pump system with energy storage
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Solution Overview
Problem
Traditional air source heat pumps experience diminished capacity and efficiency at low temperatures, and fossil fuel boilers contribute to carbon emissions and increased electrical demand during heating loads.
Innovation Solution
Incorporating a cold climate air source heat pump and thermal storage, along with additional boilers and a controller, to optimize heating operations across a wider temperature range by decoupling heat recovery from demand and utilizing energy sources opportunistically based on ambient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard air source heat pump is used, then the system is simpler and cost-effective at moderate temperatures, but heating capacity and efficiency diminish when ambient temperatures drop below zero degrees Fahrenheit
Solution Approach 1:
The heating system is segmented into multiple heat pump units with different operational characteristics. A cold climate heat pump is added specifically for low-temperature operation, while a standard heat pump handles moderate temperature conditions. This segmentation allows each unit to operate in its optimal performance range, ensuring reliable heating capacity across the full temperature spectrum without requiring one complex system to handle all conditions.
Solution Approach 2:
The thermal storage tank serves multiple functions: storing excess heat from the standard heat pump during moderate temperatures, providing supplemental heating during cold periods, and enabling heat recovery decoupling from immediate demand. This multi-functionality allows a single component to address both the reliability need for low-temperature heating and the complexity concern by consolidating several functions into one element.
2Loss of energy
If heat recovery is used, then energy efficiency improves during simultaneous heating and cooling loads, but heating support is limited when cooling loads are unavailable, especially during extreme low ambient temperatures
Solution Approach 1:
The thermal storage tank enables preliminary action by storing excess heat energy during periods when cooling loads are present and energy efficiency can be maximized through heat recovery. This stored heat is then made available for later use during extreme cold periods when cooling loads may be absent but heating demand is critical, thus decoupling heat recovery opportunities from immediate heating needs and expanding adaptability.
Solution Approach 2:
The thermal storage tank acts as an intermediary between the heat pump system and the heating load. It buffers and decouples the heat recovery process from the immediate heating demand, allowing the system to capture and store thermal energy when conditions are favorable and release it when needed, regardless of whether cooling loads are currently present. This mediator enables energy efficiency improvements to translate into reliable heating support across all conditions.
3Reliability
If fossil fuel boilers are used for heating, then heating capacity is sufficient at all temperatures, but carbon emissions increase and electrical demand rises during heating loads
Solution Approach 1:
The system changes the operational parameters of the heat pumps by adding a cold climate unit specifically designed for low-temperature operation. This cold climate heat pump maintains efficient electrical-to-thermal conversion even at extreme temperatures, replacing the need to switch to fossil fuel boilers. The parameter change in heat pump capability directly reduces carbon emissions while maintaining sufficient heating capacity across all temperature conditions.
4Adaptability or versatility
If thermal storage is implemented, then heat recovery can be decoupled from heating demand allowing opportunistic charging, but system complexity and initial cost increase
Solution Approach 1:
The thermal storage tank is designed as a multi-functional component that serves multiple purposes: enabling heat recovery decoupling, providing supplemental heating during cold periods, storing excess heat from the standard heat pump, and facilitating opportunistic charging based on energy costs and ambient conditions. By consolidating these diverse functions into a single tank, the system achieves high operational flexibility without proportionally increasing complexity, as the tank becomes a universal element addressing multiple system needs.
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 provides efficient heating even in extreme cold, reduces reliance on fossil fuels, and optimizes energy use by storing heat for later utilization, thereby enhancing efficiency and reducing carbon emissions.
Implementation Method 1
an air source heat pump configured to transfer heat from an ambient environment to the process fluid
Implementation Method 2
one or more chiller-heaters each configured to transfer heat from the process fluid to the heating fluid so as to heat the heating fluid and cool the process fluid
Implementation Method 3
a storage source energy transfer circuit comprising one or more thermal energy storage tanks, the storage source energy transfer circuit configured to circulate a process fluid
Implementation Method 4
The boiler is in series with the air source heat pump, and the boiler is configured to be operated during a defrost operation of the air source heat pump
Data Source
AI summary
A heat pump system for a building can include thermal energy storage tanks, a first air source heat pump for providing energy to the system, a second air source heat pump for providing energy to the system under cold climate conditions, and an additional heat source for supporting defrost operations and/or to provide energy under extreme cold conditions. The system can further include a controller configured to provide efficient use of energy sources to meet heating demands under extreme cold conditions.