Transcritical CO2 Heat Pump
Transcritical CO2 Heat Pump

Author: Xin-rong Zhang

Publisher: John Wiley & Sons

Published: 2021-05-10

Total Pages: 320

ISBN-13: 1118380045

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A timely and comprehensive introduction to CO2 heat pump theory and usage A comprehensive introduction of CO2 application in heat pump, authored by leading scientists in the field CO2 is a hot topic due to concerns over global warming and the 'greenhouse effect'. Its disposal and application has attracted considerable research and governmental interest Explores the basic theories, devices, systems and cycles and real application designs for varying applications, ensuring comprehensive coverage of a current topic CO2 heat transfer has everyday applications including water heaters, air-conditioning systems, residential and commercial heating systems, and cooling systems

Nordsyn study on air-to-water heat pumps in humid Nordic climate
Nordsyn study on air-to-water heat pumps in humid Nordic climate

Author: Stignor, Caroline Haglund

Publisher: Nordic Council of Ministers

Published: 2019-05-03

Total Pages: 113

ISBN-13: 9289359722

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The study presented in this report has been performed for Nordsyn sponsored by the Nordic Council of Ministers. The aim of this study was to analyse if the information given on the energy labels of air-to-water heat pumps give consumers in Nordic countries sufficient information on energy performance. When comparing results from field measurements to declared values, it shows the declared values are usually better than the field data, especially in countries with humid climate. There could be several reasons for this deviation as non-optimal installations, bypass of control systems, old field data etc. The suspicion that the deviation is due to that the standard tests do not take humidity sufficiently into account could not be proved nor fully dismissed. Recommendations are given on how this could be further investigated, including field measurements in Nordic countries.

Performance Analysis of a Transcritical CO2 Heat Pump Water Heater Incorporating a Brazed-Plate Gas-Cooler
Performance Analysis of a Transcritical CO2 Heat Pump Water Heater Incorporating a Brazed-Plate Gas-Cooler

Author:

Publisher:

Published: 2014

Total Pages: 384

ISBN-13:

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This study focuses on the experimental testing and numerical modeling of a 4.5 kW transcritical CO2 heat pump water heater at Queen's University in the Solar Calorimetry Laboratory. Due to the predicted high heat rejection temperatures in a transcritical vapour-compression cycle, buoyancy driven thermosyphon flow through a brazed-plate gas-cooler was proposed to promote tank stratification and to improve system performance. The performance was evaluated through a series of experimental sensitivity and static tank charge tests. A TRNSYS model was also created and verified to simulate the performance of the system under a detailed user demand schedule for a week of operation. The TRNSYS model used a parametric table created with a steady-state model of the vapour-compression system in EES that was validated against experimental data to a standard error of the Y-estimate of ±0.073 kW for heating capacity, ±1.01°C for gas-cooler exit temperature, and ±0.086 for COP. A series of tank charge tests were conducted under thermosyphon flow and forced flow rates at 1 L/min, 2 L/min, and 4 L/min. The thermosyphon charge test produced the highest level of stratification and a total COP of 3 at an average flow rate of 0.73 L/min. All of the forced convection cases operated with a higher degree of mixing. TRNSYS model simulations with hot water draws found that the thermosyphon flow configuration performed with a higher degree of stratification under regular user demand while simulations with high flow rates resulted in a mixed tank at a high temperature. Results predicted an 11% reduction in required heat energy input to the storage, a 30% reduction in electrical energy consumption, a 35% reduction in heat loss, and a 29% improvement in COP for the thermosyphon test as compared to the operation with a mixed tank at 4 L/min. The thermosyphon draw test also performed with the lowest average tank temperature, yet produced the highest draw temperatures. Through these results, it was concluded that natural convection operation with brazed-plate gas-coolers can contribute to a better performing system and this flow configuration should be considered in future applications of this technology.

The Economic Feasibility of Combined Heat and Power as a Utility Producer for the Residential Sector
The Economic Feasibility of Combined Heat and Power as a Utility Producer for the Residential Sector

Author: Abigail Devin Ondeck

Publisher:

Published: 2017

Total Pages: 422

ISBN-13:

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Combined heat and power (CHP) plants are a very promising prospect to reducing CO2 emissions and increasing efficiency in the power generation sector, especially when combined with residential solar photovoltaic (PV) power generation. By utilizing natural gas, a cleaner fuel than coal, CHP plants can reduce CO2 emissions, while exploiting the waste heat from electricity production to generate a useful thermal energy, increasing the overall efficiency of the plant. While incorporating residential solar PV power generation has important environmental benefits, it can - if not properly managed - lead to an over-generation situation with very high power plant ramp rates. Most current power plants are unlikely to be able to withstand such rapid changes in generation rates. If PV generation is incorporated into the design and operation of the CHP plant, both thermal and electrical energy storage systems can be included, opening the door to more strategies for controlling photovoltaic generation and increased PV power generation. The ability to combine thermal and electrical energy generation in an efficient manner, on a medium to large scale, suggests that CHP plants with rooftop PV panels and energy storage are an appealing choice as an integrated utility supplier for the neighborhood of the future. Yet, there are currently no CHP plants that serve exclusively residential neighborhoods in the United States. Thus, the objective of this research was to determine the most economical design and operation of a CHP plant with integrated residential solar PV power generation to meet all the energy demands of a residential neighborhood. After determining that a CHP plant could meet all the electricity, heating, and cooling demands of a residential neighborhood, a multi-scale economical optimization formulation to simultaneously determine the design and operation of a CHP plant with PV generation was constructed. The optimal CHP plant produced extra energy, so the optimization formulation was updated to include both thermal and electrical energy storage. Utilizing the results from these optimizations, the monetary values of PV generation and energy storage were evaluated, giving a guide for future economic targets for these technologies.

Small and Micro Combined Heat and Power (CHP) Systems
Small and Micro Combined Heat and Power (CHP) Systems

Author: R Beith

Publisher:

Published: 2011

Total Pages: 0

ISBN-13:

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Small and micro combined heat and power (CHP) systems are a form of cogeneration technology suitable for domestic and community buildings, commercial establishments and industrial facilities, as well as local heat networks. One of the benefits of using cogeneration plant is a vastly improved energy efficiency: in some cases achieving up to 80-90% systems efficiency, whereas small-scale electricity production is typically at well below 40% efficiency, using the same amount of fuel. This higher efficiency affords users greater energy security and increased long-term sustainability of energy resources, while lower overall emissions levels also contribute to an improved environmental performance. Small and micro combined heat and power (CHP) systems provides a systematic and comprehensive review of the technological and practical developments of small and micro CHP systems. Part one opens with reviews of small and micro CHP systems and their techno-economic and performance assessment, as well as their integration into distributed energy systems and their increasing utilisation of biomass fuels. Part two focuses on the development of different types of CHP technology, including internal combustion and reciprocating engines, gas turbines and microturbines, Stirling engines, organic Rankine cycle process and fuel cell systems. Heat-activated cooling (i.e. trigeneration) technologies and energy storage systems, of importance to the regional/seasonal viability of this technology round out this section. Finally, part three covers the range of applications of small and micro CHP systems, from residential buildings and district heating, to commercial buildings and industrial applications, as well as reviewing the market deployment of this important technology. With its distinguished editor and international team of expert contributors, Small and micro combined heat and power (CHP) systems is an essential reference work for anyone involved or interested in the design, development, installation and optimisation of small and micro CHP systems. Reviews small- and micro-CHP systems and their techno-economic and performance assessment Explores integration into distributed energy systems and their increasing utilisation of biomass fuels Focuses on the development of different types of CHP technology, including internal combustion and reciprocating engines.