District Heat Pump Cycle Using Direct Water Evaporation
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Solution Overview
Problem
Existing heat pump systems are inefficient in district heating networks, particularly during hot periods, as they rely on air-cooled condensation and are limited by surrounding air temperatures, leading to poor performance and thermal losses.
Innovation Solution
A thermally driven heat pump apparatus that utilizes direct evaporation and condensation of district heating water within the system, eliminating the need for heat exchangers and air-cooled condensation, allowing for efficient energy transfer and optimized usage of district energy networks by leveraging the temperature difference in the grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If air-cooled condensation is used in existing heat pump systems, then the system can operate with simpler condensation infrastructure, but the system performance deteriorates during hot periods due to dependence on surrounding air temperatures
Solution Approach 1:
The patent introduces district heating water as an intermediary cooling medium instead of using air directly. The condenser transfers heat to district heating water, which then carries the thermal energy away through the district heating network. This mediator eliminates the direct dependence on ambient air temperature while still providing effective heat rejection, resolving the contradiction between infrastructure simplicity and hot-weather performance.
2Loss of energy
If direct evaporation of district heating water is implemented, then thermal losses are reduced and energy transfer efficiency is improved, but the system complexity increases due to direct contact between process fluid and working fluid
Solution Approach 1:
The patent merges the evaporator and condenser functions into a single direct contact heat exchange process. District heating water directly evaporates to drive the turbine, combining the cooling and power generation functions. This eliminates the need for separate heat exchanger surfaces and reduces thermal losses by eliminating intermediate heat transfer steps, while the overall system complexity remains manageable through functional integration.
3Use of energy by moving object
If heat exchangers are used for heat transfer, then thermal energy can be transferred between fluids, but thermal losses increase and energy transfer efficiency decreases
Solution Approach 1:
The patent extracts and eliminates the heat exchanger component from the thermal energy transfer path. Instead of using heat exchangers to transfer heat from district heating water to the working fluid, the system allows direct evaporation of district heating water. This removal of the heat exchanger intermediate step eliminates the associated thermal losses and improves energy transfer efficiency directly.
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 solution enhances the performance of district heating systems by enabling efficient energy transfer and cooling, reducing thermal losses, and allowing for optimal operation during hot seasons, independent of air temperatures, with a cascading effect that can cool multiple units using a single heat pump.
Implementation Method 1
an evaporator, such as an evaporation tank configured to evaporate by direct evaporation a liquid received from an external liquid source
Implementation Method 2
the pressure in the evaporation chamber being lower than the pressure in the liquid inlet line and sufficient low for evaporating the liquid entering the evaporation chamber
Implementation Method 3
The generated gas fluid is passed through an expander turbine, which converts the thermal energy into mechanical energy
Implementation Method 4
the compressor being operatively driven by the expander for compressing a gas from a low pressure, low temperature inlet gas at the compressor inlet to a high pressure, high temperature outlet gas at the compressor outlet
Implementation Method 5
a first condenser having a first condenser inlet and a first condenser outlet, the first condenser inlet having a fluid connection to the expander outlet and being configured for condensing the fluid received from the expander
Data Source
AI summary
The present invention provides a heat pump apparatus comprising a Rankine cycle and an Carnot cycle part when implemented for cooling. The Rankine cycle comprises an evaporator configured for evaporating by direct evaporation water received from an external water source. An expander receives steam from the evaporator and drives a compressor compressing the fluid of the Carnot cycle. The fluid is thereafter condensed in a condenser and evaporated in an absorber.