C211 ヒートポンプを用いた蒸気熱搬送装置(熱交換1)

Fuzzy control of calcium carbonate and silica scales in geothermal systems

Water heating represents approximately 18% of residential energy consumption, or 4.6 quadrillion Btus of source energy use annually (EIA 2009). Heat pump water heaters (HPWHs) offer an efficient option for residential water heating, with the ability to reduce water heating energy consumption by up to 63%. Previous research has demonstrated the laboratory performance of HPWHs and has shown savings of 43 to 62% on water heating energy consumption are possible, based on field tests (Ecotope 2015). In order to achieve such high efficiencies, HPWHs employ a refrigeration cycle to move heat from the ambient air into the water. Therefore, when HPWHs are installed in conditioned space, they will remove heat from that space which can help the HVAC system in the cooling season and require additional energy from the HVAC system in the heating season. This project provides an unbiased evaluation of the space conditioning interactions between a HPWH and the heating system in several locations throughout the home to further our understanding of the impact that HPWHs have on space conditioning loads. This report explores the HPWH interaction factor from several perspectives: (1) a theoretical analysis, (2) a review of previous literature, and (2) an experimental assessment. The experiments were conducted in PNNL’s side-by-side Lab Homes, which provide a platform for evaluating energy-saving and grid-responsive technologies in a controlled environment. The PNNL Lab Homes are two factory-built homes installed on PNNL’s campus in Richland, Washington. The homes represent existing homes, which account for approximately 99% of occupied homes in the U.S. These 1500 ft2 homes have three bedrooms, two bathrooms, and are equipped with 7.7 HSPF heat pump and an electric forced air furnace. Both homes have R-22 floors, R-11 walls and R-22 ceiling insulation levels, with double-pane clear glass windows. The results of this experiment verified that the energy use of the HVAC system increases as a point source cooling load, like a HPWH, is moved closer to the thermostat. The opposite is also true, as a point source heating load is moved closer to the thermostat, the heating load decreases. The results show between 30-40% difference between the interaction that this type of load has when it is placed in the master bathroom compared to the living room for the PNNL Lab Homes.

The Denver Museum of Nature & Science (DMNS) designed and implemented an innovative ground source heat pump (GSHP) system for heating and cooling its new Education and Collection Facility (ECF) building addition. The project goal was to successfully design and install an open-loop GSHP system that utilized water circulating within an underground municipal recycled (non-potable) water system as the heat sink/source as a demonstration project. The expected results were to significantly reduce traditional GSHP installation costs while increasing system efficiency, reduce building energy consumption, require significantly less area and capital to install, and be economically implemented wherever access to a recycled water system is available. The project added to the understanding of GSHP technology by implementing the first GSHP system in the United States utilizing a municipal recycled water system as a heat sink/source. The use of this fluid through a GSHP system has not been previously documented. This use application presents a new opportunity for local municipalities to develop and expand the use of underground municipal recycled (non-potable) water systems. The installation costs for this type of technology in the building structure would be a cost savings over traditional GSHP costs, provided the local municipal infrastructure was developed. Additionally, the GSHP system functions as a viable method of heat sink/source as the thermal characteristics of the fluid are generally consistent throughout the year and are efficiently exchanged through the GSHP system and its components. The use of the recycled water system reduces the area required for bore or loop fields; therefore, presenting an application for building structures that have little to no available land use or access. This GSHP application demonstrates the viability of underground municipal recycled (non-potable) water systems as technically achievable, environmentally supportive, and an efficient system.

Decarbonisation of domestic heating in the UK is expected to involve widespread replacement of gas boilers with heat pumps. This transition requires a reduction in heating system flow temperature for the heat pump to operate efficiently, which can necessitate costly radiator or fabric upgrades to provide sufficient heat. The requirements for existing dwelling and heating systems to have these upgrades therefore directly impacts the “heat pump readiness” of the UK stock. This paper applies a novel approach in using diagnostic data for approximately 4600 boilers to evaluate the viability of installing heat pumps with no changes made to the existing radiators or fabric. Results indicate that 31% of dwellings in the sample could operate with Low Temperature Heat Pumps (LTHPs) without upgrades to radiators or fabric, or up to two thirds with High Temperature Heat Pumps (HTHPs), whereas previous analysis using surveys has found that radiator upgrades are almost always needed. Therefore, the costs and disruption of heat pump roll out could be substantially lower than previously predicted, and the use of real heating system performance data could supplement survey-based assessments of heat pump readiness to help identify more accurately where upgrades are needed. Practical application Current design practices almost always lead to replacement of existing radiators when switching a gas boiler for a heat pump. However, analysis of diagnostic data from approximately 4600 boilers in the UK suggests this may not be entirely necessary. This measured heating system data indicates that up to two-thirds of UK dwellings could operate with High Temperature Heat Pumps (HTHPs) without upgrading existing radiators. Henceforth, development of data-driven testing procedures for the design of future heating systems has significant potential to facilitate rapid heat pump deployment at a national scale, a crucial step in decarbonising buildings in the UK.

Feasibility Analysis of Building Heating System Based on Thermal-Economical Evaluation

Effect of heating system using a geothermal heat pump on the production performance and housing environment of broiler chickens

Solar district heating systems are essential in reducing carbon emissions and alleviating the energy crisis. By integrating with air-to-water heat pumps, it is possible to enhance the system’s efficiency and flexibility. However, the complementary mechanisms and coupling effects between the heat pump and the other components of the system are not clear. To address these issues, it is necessary to investigate the thermo-economic performance of the system, taking into account energy price fluctuations to achieve a more efficient and economically viable operational model. This study focuses on a solar district heating system in the Danish city of Ørum and investigates the impact of integrating a large-scale air-to-water heat pump. Based on energy and economic analyses, the impact of the heat pump on the system efficiency and the levelized cost of heat are investigated for 2020 and 2022. The results show that the heat pump can convert low-cost electricity into heat which will be stored in the tank, increasing the tank’s heat storage content by 1.2 times. The medium to low-temperature water in the tank can preheat the heat pump’s compressor, raising the COP of the heat pump from 3.3 to 3.5 and increasing the annual utilization cycle of the tank by 1.4 times by reducing the return water temperature to the bottom of the tank. Additionally, the system performance has been improved due to the installation of the heat pump, which increased the system COP from 1.22 in 2020 to 2.62 in 2022. Subsequently, the CO2 emission has been decreased from 192 kg/MWh to 74 kg/MWh with a larger share of sustainable energy. Due to the heat pump operation, the system-levelized cost of heat could be reduced to 68.6 EUR/MWh, compared to 94 EUR/MWh if the heat pump is removed. The investigation also revealed that the heat pump improved the flexibility of the heating system in response to energy prices, especially during the 2022 energy crisis in Europe. The findings of the paper provide a good reference for large solar heating applications.

Navajo (Diné) tribal members experience alarming rates of diabetes and food insecurity on the reservation. Increasing involvement with food production through gardening is a crucial step to rebuilding Diné food systems and improving the health of Navajos. The main challenges are drought, lack of available land, limited food production knowledge, and large up-front costs. However, implementing community-based gardens would help alleviate land space issues, leverage community knowledge, and shift financial responsibility to local community level or chapter level. Greenhouses are advantageous because they reduce water consumption and allow for year-round production, but require energy intensive heating, ventilation, and air conditioning (HVAC) systems. Therefore, the purpose of this paper is to compare a propane heating and evaporative cooling HVAC system to a ground source heat pump (GSHP). Using EnergyPlus to simulate annual energy loads, this paper compares the financial feasibility and environmental impact of each system. The operating cost of GSHPs was found to be 57% — 72% less than traditional HVAC systems based on location and fuel prices. Additionally, GSHPs required 72% — 90% less water and emitted 35% — 69% less carbon dioxide annually. Given the large up-front cost of GSHPs, conservative estimates showed payback periods from 5.2 — 10.8 years when using renewable energy grants. A life cycle cost analysis over 20 years showed greenhouses with GSHPs could cost $1,272 — $1,605 per year or 27% — 44% less than traditional HVAC systems. Tax revenue for chapters showed that funding is available to carry out such projects. Food produced using GSHP systems was found to cost $2.26 — $2.30 per daily serving of fruit and vegetables, which is competitive with grocery store prices. More importantly, greenhouses equipped with GSHPs present a compelling case because they cost less to operate and are more environmentally friendly than traditional HVAC systems. Future work should focus on adding a photovoltaic (PV) and battery storage system, which would completely eliminate HVAC water consumption and carbon dioxide emissions.

The ground-source heat pump is a system which takes the shallow surface soil energy as the source of heating and cooling. The temperature of ground source is relatively stable throughout the year, which makes the ground-source heat pump have the higher operation efficiency compared with the traditional air-conditioning system.Study on the ground-source heat pump with properties of thermal dynamics used in heating and air comditioning by ecomomic analysis is still an important issue. In this paper, the ground-source heat pump and the traditional heating and air-conditioning system have been compared in terms of their economic competitiveness. Firstly, it is required to compare the ground-source heat pump with the traditional heating method in terms of the heating economy. Afterwards, it is necessary to compare the ground-source heat pump with the conventional electric refrigeration in terms of the air-conditioning economy. Finally, it is needed to conduct the comprehensive and economic analysis for the ground-source heat pump and the boilers and air conditioning, which includes four programs.

This thesis investigates factors affecting demand for heat pumps in the residential sector in England and Wales. There are three objectives: to identify the macroeconomic and sociodemographic factors, environmental aspects, climatic conditions and policies that led to the mass deployment of heat pumps in other European countries; to assess the optimal level of heat pump adoption from a societal perspective taking account of environmental externalities; and to identify policies that could result in the mass-market deployment of heat pumps in the UK. Following reviews of studies on consumer preferences for heating systems, and markets and policies to promote heat pumps in eight European countries, two quantitative approaches are followed. The first is an econometric model based on panel data which estimates the impact of macroeconomic, sociodemographic and environmental factors on the demand for heat pumps in Austria, Finland, France, Germany, Sweden, Switzerland and the UK. The role played by three types of policies, financial/fiscal, informative and legislative, is investigated. These are found to have been significant factors in promoting heat pump take-up. A bottom-up techno-economic model simulating the choice of heating systems in the existing housing stock in England and Wales is then developed and is used to assess optimal heat pump take-up and policies that might promote their adoption. Capital cost subsidies, used in most European countries, are considered alongside the Renewable Heat Incentive approach adopted in the UK. The implications of adding the policy costs of support for renewable energy and energy efficiency to electricity prices, tilting the market against electric technologies, are also considered. The thesis concludes that financial incentives are needed to build heat pump markets, but they are not enough in themselves. Building supply chains, driving down costs and improving the performance of heat pumps are also essential.

Performance analysis on compression-assisted absorption heat transformer: A new low-temperature heating system with higher heating capacity under lower ambient temperature

On the value of combined heat and power (CHP) systems and heat pumps in centralised and distributed heating systems: Lessons from multi-fidelity modelling approaches

By 2020 all new buildings within the European Union should reach nearly zero energy level. Their energy needs should be significantly covered by renewable energy sources. As a consequence, it is important to identify which combinations of technologies will be suitable in order to reach such objectives. Climate conditions, final energy and investment costs, technological maturity and stakeholders’ services quality are key elements for the final choice. This paper presents some results of a more general survey the purpose of which is to study different combinations of heating systems integrated in single-family dwellings under the Belgian climate conditions. The heating system that is concerned is a solar heating system with a ground heat storage and a geothermal heat pump that exhibits energy performance in agreement with such future building standards. This system works with solar collectors which produce heat for space heating (SH) and domestic hot water preparation (DHW). This thermal energy is distributed to the building - using a short-term storage - when it is needed or stored in the DHW tank. If the production is in excess, the energy is stored into the ground using a borehole heat exchanger. This energy will then be used by a geothermal heat pump when the solar collectors cannot fulfil the building heating needs. A design procedure has been developed and tested on several buildings using simulation tools. The borehole depth ranges from 150 m to 350 m and the solar collectors areas from 22 m2 to 46 m2 depending on the energy performance of the building. The procedure permits to reach a renewable coverage ratio higher than 80% (instead of 55% for solar heating coupled with a geothermal heat pump without storage). Results are presented for one building. The system performance is compared to that of a reference system (most likely to be used in practical case): air to water heat pump without any solar assistance.

In the European Union (EU), buildings are responsible for about 40% of the total final energy consumption, and 36% of the European global CO2 emissions. The European Commission released directives to push for the enhancement of the buildings energy performance and identified, beside the retrofit of the current building stock, Heating, Ventilation, and Air Conditioning (HVAC) systems as the other main way to increase renewable energy sharing and overall building energy efficiency. For this purpose, Ground Source Heat Pumps (GSHPs) represent one of the most interesting technologies to provide energy for heating, cooling, and domestic water production in residential applications, ensuring a significant reduction (e.g., up to 44% compared with air-source heat pumps) of energy consumption and the corresponding emissions. At present, GSHPs mainly employ the refrigerant R410A as the working fluid, which has a Global Warming Potential (GWP) of 2087. However, following the EU Regulation No. 517/2014 on fluorinated greenhouse gases, this high GWP refrigerant will have to be substituted for residential applications in the next years. Thus, to increase the sustainability of GSHPs, it is necessary to identify short time alternative fluids with lower GWP, before finding medium-long term solutions characterized by very low GWP. This is one of the tasks of the UE project "Most Easy, Efficient, and Low-Cost Geothermal Systems for Retrofitting Civil and Historical Buildings" (acronym GEO4CIVHIC). Here, a thorough thermodynamic analysis, based on both energy and exergy analysis, will be presented to perform a comparison between different fluids as substitutes for R410A, considered as the benchmark for GSHP applications. These fluids have been selected considering their lower flammability with respect to hydrocarbons (mainly R290), that is one of the main concerns for the companies. A parametric analysis has been performed, for a reversible GSHP cycle, at various heat source and sink conditions, with the aim to identify the fluid giving the best energetic performance and to evaluate the distribution of the irreversibilities along the cycle. Considering all these factors, R454B turned out to be the most suitable fluid to use in a ground source heat pump, working at given conditions. Special attention has been paid to the compression phase and the heat transfer in evaporator and condenser.

The Sonoma State Mental Hospital, located in Eldridge, California, is presently equipped with a central gas-fired steam system that meets the space heating, domestic hot water, and other heating needs of the hospital. This system is a major consumer of natural gas - estimated at 259,994,000 cubic feet per year under average conditions. At the 1981 unit gas rate of $0.4608 per therm, an average of $1,258,000 per year is required to operate the steam heating system. The hospital is located in an area with considerable geothermal resources as evidenced by a number of nearby hot springs resorts. A private developer is currently investigating the feasibility of utilizing geothermally heated steam to generate electricity for sale to the Pacific Gas and Electric Company. The developer has proposed to sell the byproduct condensed steam to the hospital, which would use the heat energy remaining in the condensate for its own heating needs and thereby reduce the fossil fuel energy demand of the existing steam heating system. The geothermal heating system developed is capable of displacing an estimated 70 percent of the existing natural gas consumption of the steam heating system. Construction of the geothermal fluid distribution and collection system and the retrofits required within the buildings are estimated to cost $1,777,000. Annual expenses (operation and maintenance, insurance, and geothermal fluid purchase) have been estimated to be $40,380 per year in 1981 dollars. The proposed geothermal heating system could then be completely paid for in 32 months by the savings in natural gas purchases that would result.