The short-cycling operation of a heat pump decreases energy consumption efficiency. Short-cycling operations of GSHP (Ground Source Heat Pump System) occur when the ON / OFF control of a heat pump is used a partial load condition. It is considered effective that GSHP with capacity controls installs to suppress short-cycling operations. However, there is no report on any continuous operations by capacity control GSHP in actual operations. We confirmed that GSHP (water to water) with capacity control operates short-cycling in the residence. Short-cycling operations were occurred a sudden load fluctuation due to opening or closing of the valves. We conducted effective verification experiments of the thermal storage device at the artificial heat load fluctuations condition. When the thermal storage device installed upstream brine circulation line of the heat pump with the capacity control, continuous operations are performed. It was under the condition at the heating heat load of 5 kW is turned ON / OFF every 20 minutes. In this case, energy consumption efficiency of a heat pump is 13% higher than the efficiency without the thermal storage device.

In order to reduce CO 2 emissions in the residential sector, the installation of photovoltaics (PV) has been increasing extensively. However, such large-scale PV installations cause problems in the low-voltage distribution grid of the residential sector, such as PV related voltage surges. In this study, the utilization of suppressed PV output through energy storage devices was proposed. Using demand side energy storage devices reduces voltage surge, transmission loss, and CO 2 emissions from the residential buildings. The objective of this study was to add voltage constraints of the low-voltage distribution grid to an operational planning problem that we developed for the residential energy systems, and to quantitatively evaluate the potential of heat pump water heater (HP) to utilize the PV surplus electricity, while considering the electrical grid constraints based on the minimization of CO 2 emissions. We found that when a 4.5 kW HP with 370 L storage, which utilizes PV output, was added to the system, the reduction in CO 2 emissions was more than twice compared with that in the case of adding 4 kWh battery (BT) to a PV and gas fired water heater configuration. Further, the effect of utilizing the suppressed PV electricity by HP was almost equivalent to that by the BT. Therefore, the potential of HP in utilizing PV surplus electricity is higher than that of the BT in terms of CO 2 emissions reduction in the residential sector.

Cyber-physical systems (CPS) are smart systems that include engineered interacting networks of physical and computational components. The tight integration of a wide range of heterogeneous components enables new functionality and quality of life improvements in critical infrastructures such as smart cities, intelligent buildings, and smart energy systems. One approach to study CPS uses both simulations and hardware-in-the-loop (HIL) to test the physical dynamics of hardware in a controlled environment. However, because CPS experiment design may involve domain experts from multiple disciplines who use different simulation tool suites, it can be a challenge to integrate the heterogeneous simulation languages and hardware interfaces into a single experiment. The National Institute of Standards and Technology (NIST) is working on the development of a universal CPS environment for federation (UCEF) that can be used to design and run experiments that incorporate heterogeneous physical and computational resources over a wide geographic area. This development environment uses the High Level Architecture (HLA), which the Department of Defense has advocated for co-simulation in the field of distributed simulations, to enable communication between hardware and different simulation languages such as Simulink ® and LabVIEW ® . This paper provides an overview of UCEF and motivates how the environment could be used to develop energy experiments using an illustrative example of an emulated heat pump system.

Distributed peak-shaving heat pump technology is to use a heat pump to adjust the heat on the secondary network in a substation, with features of low initial investment, flexible adjustment, and high operating cost. The paper takes an example for the system that uses two 9F class gas turbines (back pressure steam) as the basic heat source and a distributed heat pump in the substation as the peak-shaving heat source. The peak-shaving ratio is defined as the ratio of the designed peak-shaving heat load and the designed total heat load. The economic annual cost is taken as a goal, and the optimal peak-shaving ratio of the system is investigated. The influence of natural gas price, electricity price, and transportation distance are also analyzed. It can provide the reference for the optimized design and operation of the system.

In order to reduce the quantity of CO 2 emissions economically, it is important to construct a Smart Community which is expected to be one of the solutions. In a Smart Community, energy supply and demand system is developing to manage with ICT (Information and Communication Technology) to utilize energy efficiently and increase the amount of renewable energy. In one of the systems, “Photovoltaic power generator (hereinafter referred to as PV) & Electric Vehicle (hereinafter referred to as EV) Smart System” has been developed. In the “PV & EV Smart System”, PV power is charged directly to the EV battery, and then the charged PV power is consumed by running and air-conditioning energy of a car and supplied to a home. This system is able to reduce the quantity of CO 2 emissions with high economic efficiency. In order to expand the system, it is necessary to spread EV. So, it should solve the issues of short driving distance, the high cost of storage battery and the risk of dead battery. Therefore, the authors have proposed an advanced EV such as AI-EV (Air-conditioner Integrated Electric Vehicle). AI-EV has a novel hybrid system which drives the air-conditioning system and generates electric power in the case of a low air-conditioning load through the use of a small-engine. PV power can not only reduce car fuels but also replace with gas and liquid fuels which are used at a home, causing the huge effect of reducing CO 2 emissions as the whole system. In this paper, a novel energy system which is integrated with solar power, advanced electric vehicle and CO 2 heat pump water heater as home heat pumps has been proposed. A mathematical simulation model which evaluates for the PV power generation, AI-EV energy consumption and home heat pumps has been developed. CO 2 emissions and economic efficiency are calculated and compared with those of the conventional system. As the result, the novel energy system is able to reduce more than 30% of the quantity of CO 2 emissions in comparison with the conventional system as the whole system, and the system can reduce about 60% of the quantity of CO 2 emissions in comparison with the conventional system as a home system. The economic efficiency is evaluated by more than 6.0% of IRR (Internal Rate of Return) without some subsidies when the legal service life of the depreciation equipment is assumed 14 years. Therefore, the novel energy system can be widely spread in the future.

Buildings are widely recognised as key contributors to global energy use and emissions. Approximately 50% of the energy consumption of the non-domestic buildings is due to Heating Ventilation and Air-Conditioning (HVAC) systems. Therefore, there is great potential in improving the energy performance of buildings, by investigating the deployment of low-carbon HVAC technologies. HVAC system selection is usually performed in early design stages, when there is high uncertainty associated with the system’s requirements. To deal with these uncertainties, Global Sensitivity Analysis (GSA) can be deployed. GSA can systematically identify the most important variables, in terms of their impact on system performance. This study considers the usefulness of GSA in designing HVAC systems with an office building case study. GSA identifies the heat pump and heat recovery efficiencies as the most significant uncertain parameters. These, account for more than 90% of the observed variation in the energy consumption. Additionally, the results reveal that by selecting a heat pump capacity at 80% of the potential annual peak load point estimate, there is 95% probability for the system to satisfy the peak demand at any given hour. The analysis demonstrates the potential of GSA in informing the design of novel HVAC and power generation technologies.

In European countries seasonal thermal energy storage is an emergent task due to availability of solar energy in summer and thermal energy demand in winter. In this study the performance of an uninsulated buried storage tank is analyzed. Summer temperatures reached 45 °C in the storage tank and 22 °C in the soil, 1 m from the tank shell. Wintertime temperature of the storage tank dropped to 8 °C, near the freezing limit of the heat pump, and soil cooled down to 9 °C. While in wintertime heat transfer from earth to water was the limiting factor, a summertime temperature difference of more than 20 °C allowed enough energy transport to charge the soil storage system. An analytical model showed that more than 50% of the solar energy stored could be recovered by this application.

All life on earth depends on energy and the cycling of carbon. Energy is essential for economic and social development and also poses an environmental challenge. The world’s dependence on fossil fuels began approximately 200 years ago. Availability of fossil energy resources, peak oil era and this is the time for end of the fossil fuel era, price and environmental impact and various renewable resources and use of it. The twenty first century is rapidly becoming the perfect energy storm, modern society is faced with volatile energy prices and growing environmental concerns as well as energy supply and security issues. Solar and wind energy are now providing the lowest cost options for economic and community development in rural regions around the globe. Energy and water are the key to modern life and provide the basis necessary for sustained economic development. Due to a growing world population and increasing modernization global energy demand is raising during the current century. Finding the sufficient supplies of clean and sustainable energy for the future is the global society’s most challenge for this century. The future will be depends on a renewable sources such as solar, wind and biomass. There are large numbers of phase change materials (PCM’S) that melt and solidify at wide range of temperatures, making them attractive in a number of applications. PCMs have been widely used in latent heat thermal storage systems for heat pumps, solar engineering and spacecraft thermal control applications. The use of PCMs for heating and cooling applications for buildings has been investigated within the past decade. The experimental results computed in the field of water distillation process using solar energy in the presence of energy storage materials i.e paraffin wax are discussed in this paper.

A ground source heat reference map (GSHRM) shows the minimum necessary thermal performance of the ground heat exchanger (GHE) of a ground source heat pump (GSHP) system. Thermal performance depends on thermal properties of the ground, the ground temperature profile, heat advection by groundwater flow, and the GHE operating pattern. This study modeled optimum heating and cooling modes for a GSHRM. First, continuous and intermittent operation modes were compared, and a standard operation time was defined. In a standard household GSHP system, the quantity of heat transferred from the ground depends on household energy demand, which is relatively constant. Once the demand is known, an operation mode is selected that can meet it. Continuous operation increased the total amount of heat exchanged over a period of time but lowered the heat flux at the GHE, whereas intermittent operation with relatively long stopped periods decreased the total amount of heat but did not greatly decrease the heat flux at the GHE. Second, energy-saving efficiency and cost factors were compared among intermittent operation modes. Operation costs consist of the electrical energy supplied to the heat and circulation pumps. At a given operation time, the energy supplied to the heat pump depends on its coefficient of performance (COP), whereas that supplied to the circulation pump depends on its pressure loss, hence on the GHE length. A long GHE has a higher initial cost. Thus, the optimum heating pattern must consider the configuration of the GSHP system, including energy-saving efficiency and cost factors.

The design of expanders for organic fluids is gaining an increasing attention due to the large opportunities opened by the ORC as a way to recover low grade heat. The possibility of recovering at least a fraction of the energy related to throttling in inverse cycles could have interesting relapses on the market of heating (heat pumps) and refrigeration machines. The main challenge to be faced is the management of a highly wet fluid (typical quality is in the 0–0.6 range), which puts off side dynamic expanders like turbines. For this reason, piston technology is proposed and analyzed. The potential recovery from the throttling of a 20 kW target domestic heat pump cycle is determined by modeling the real expansion cycle with two different codes, a commercial one (largely widespread and very easy to use) and a purposely developed one, which is much more customizable and may include different approaches to the physical behavior of the two–phase expansion. The results show interesting possibility of energy recovery from this generally wasted source, which opens the way to improvements of the heat pump COP from 4% to about 7%, depending on the working (i.e. seasonal) conditions. The analysis also points out the agreement in the results of two different adopted simulation tools (commercial AMESim ® and self-made customizable EES ® ), which can be thus considered valuable in the design, analysis and optimization of the proposed expander. Due to the biphasic nature of the working fluid, the performance of the expander is strongly influenced by the inlet conditions of the fluid from the condenser of the heat pump to the cylinders, such as throttling of the inlet/outlet valves and friction through the ducts. On the whole, this expander technology has very interesting chances to effectively manage fluids under highly wet conditions, like those related to the throttling from upper to lower pressure of inverse cycles.

Carbon dioxide’s use as an alternative refrigerant has been increasing in popularity due to its low global warming and ozone depletion potentials. In recent years, a number of companies and researchers have investigated applications of CO 2 heat pumps for water heating. This study investigates the experimental testing of a CO 2 heat pump water heater (HPWH) at Queen’s University. For the tests, the conventional factory gas-cooler on an Eco-cute unit and air-source evaporator was replaced with a specially designed brazed-plate gas-cooler. It rejected heat to a 273 litre hot water and the evaporator sourced heat from a warm water supply. Experiments were conducted using both forced and natural convection (i.e., thermosyphon) flow between the gas-cooler and hot water tank. Thermosyphon flow was studied to evaluate its effects on storage tank stratification and heat pump operation (i.e., coefficient of performance). Results were compared to forced circulation cases run over a range of flow rates. In the forced convection flow test, it was observed that a decrease in gas-cooler average water temperature increased the coefficient of performance (COP) non-linearly and an increase in the water-side flow rate increased the COP and the effectiveness of the gas-cooler. The thermosyphon had an average flow rate of 0.75 L/min and an average COP of 3.1. Thermosyphon flow kept the hot water tank fully stratified until fully charged. Water was delivered at an average of 70°C. It was also observed that thermosyphon flow rate depended on the state of charge (i.e., temperature distribution) in the storage tank. In order to increase the performance, a gas-cooler with a lower pressure drop should be used to increase the thermosyphon flow rate.

Groundwater source heat pumps exploit the difference between the ground surface temperature and the nearly constant temperature of shallow groundwater. This project characterizes two areas for geothermal heating and cooling potential, Mason County in central Illinois and the American Bottoms area in southwestern Illinois. Both areas are underlain by thick sand and gravel aquifers and groundwater is readily available. Weather data, including monthly high and low temperatures and heating and cooling degree days, were compiled for both study areas. The heating and cooling requirements for a single-family house were estimated using two independent models that use weather data as input. The groundwater flow rates needed to meet these heating and cooling requirements were calculated using typical heat pump coefficient of performance values. The groundwater in both study areas has fairly high hardness and iron concentrations and is close to saturation with calcium and iron carbonates. Using the groundwater for cooling may induce the deposition of scale containing one or both of these minerals.

This paper presents an analysis of an organic Rankine cycle (ORC) with dry cooling system aided by an earth-coupled passive cooling system. Several organic fluids were considered as working fluids in the ORC in the temperature range of 125–200°C. An earth-air-heat-exchanger (EAHE) is studied for a location in the United States (Las Vegas) and another in India (New Delhi), to pre cool the ambient air before entering an air-cooled condenser (ACC). It was observed that the efficiency of the system improved by 1–3% for the system located in Las Vegas and fluctuations associated with temperature variations of the ambient air were also reduced when the EAHE system was used. A ground-coupled heat pump (GCHP) is also studied for these locations where cooling water is pre cooled in an underground buried pipe before entering a condenser heat exchanger in a closed loop. The area of the buried pipe and the condenser size are calculated per kW of power generation for various working fluids.

TRNSYS simulation software was used to modify a validated Air Source Heat Pump (ASHP) model in an Archetype Sustainable House (ASH) in Toronto. In this model, a Building Integrated Photovoltaic-Thermal Collector (BIPV/T) was coupled with ASHP. The PV/T system arrangement was considered as a part of the south-oriented roof of the house. The warm air generated in the BIPV/T collector was considered the source of the heat pump for heat production. The coupling of BIPV/T and ASHP enables a highly efficient heating system in harsh winter conditions. The developed TRNSYS model of the house along with integrated PV/T system with ASHP was simulated for the whole year to predict the hourly outlet air temperature, thermal energy and electricity obtained from the PV/T array. The results from the simulation were used to estimate the saving in energy and cost as well as to predict the electricity related GHG emission reduction potential from the PV panels. Monthly greenhouse gas (GHG) emission credit from PV production based on hourly GHG emission factor was obtained; the results showed that annual GHG emission due to electricity demand by the ASHP was reduced by 225 kg CO 2 (19.3%) when the heat pump was integrated with the PV/T array. Also, in this study, the annual electricity cost credit from PV production based on Time-of-Use (TOU) and the reduction in electricity cost of the heat pump when connected with PV/T systems was calculated and compared with the cost of working the heat pump alone. The results show that there is a saving of $500 in annual electricity bills and GHG emission credit of 862.6 kg CO 2 from renewable electricity generation.

A theoretical investigation of a variable capacity air-to-air air source heat pump (VC-ASHP) coupled with a building integrated photovoltaic/thermal (BIPV/T) system is presented in this paper. The BIPV/T system was integrated into the roof and the wall. Air was circulated behind the photovoltaic arrays to recover the thermal energy. The warm air recovered was supplied to the VC-ASHP. The thermal performance of the VC-ASHP was investigated for three scenarios when the heat pump is running in heating mode. The three scenarios are: (A) by feeding the ambient air to the ASHP; (B) by coupling the ASHP to the wall integrated BIPV/T only; and (C) by coupling the ASHP to the roof integrated BIPV/T only. The coefficient of performance (COP) of the VC-ASHP was evaluated for these three separate scenarios and compared. A typical winter day result suggests that the COP of the ASHP can be improved by coupling the VC-ASHP to either of the BIPV/T systems, i.e., either to the roof integrated BIPV/T system or to the wall integrated BIPV/T system.

A unique autonomous control system was developed to manage the HVAC components of a residence built specifically for an ultra-efficient home competition. Some of the home’s HVAC components that contribute to its ultra-efficiency (and necessitate such an autonomous controller) include multiple ductless mini-split heat pumps, multiple hydronic heated floor loops, multiple circulating ceiling fans, and a closed-loop solar thermal collection and storage system that not only provides hot water to the hydronic heated floors, but also supplies the home with domestic hot water. The autonomous controller integrates all this equipment with a mixture of technology that includes power-line communications, both wired and wireless TCP/IP network signals, low-voltage wiring, and infrared signals. By utilizing these many different methods to communicate with equipment around the home, the controller is able to simultaneously regulate components and systems that are often considered “stand alone” or impractical to implement in residential buildings due to their need for constant manual operation. The result is an HVAC system that consumes very little energy while still providing an expected level of comfort.

Subcooling of the refrigerant at the exit of the condenser in a vapor compression refrigeration system could be an effective method to improve the coefficient of performance (COP). This method allows the refrigerant entering the evaporator with a lower mass fraction of vapor and absorbs more heat in the evaporator. The effort in this paper investigates a solar based integrated system of an electricity-driven vapor-compression chiller (VC) and an absorption heat pump (ABS) to provide both heating and cooling to space. Thermodynamic and heat transfer models of the integrated system were developed to estimate the system performance. The modeling results showed the integrated system can achieve 40% of the reduction on electricity consumption and 66% of the improvement in cooling COP. Furthermore, the hot water supply temperature can reach 50.25°C. The models have also been used to conduct parametric sensitivity analysis. The key parameters which affect the performance of the system were the heat source temperature, the hot water return temperature, and the outdoor air flow rate. Hot water flow rate only has significant influence on the hot water supply temperature. Increasing the temperature and flow rate of the heat source can have benefits on both heating and cooling performance. However, increasing the outdoor air flow rate can only benefit on energy saving and cooling performance.

Approximately half of the water heaters sold in the U.S. and Canada for residential and small commercial applications are natural gas fired storage water heaters, with a maximum theoretical thermal efficiency of 96%. A packaged water heater heated by a 2.9 kW absorption heat pump was designed and demonstrated in this study to achieve performance exceeding these limitations. The modeling and validation of the absorption cycle and of the natural gas-fired combustion system are discussed here. Heat transfer characteristics of the absorption components at expected operating conditions were used to model cycle performance. A single-effect system based on these models was fabricated and yielded a cyclic COP of 1.63, within 3% of predictions. A corresponding GAX cycle-based system yielded performance 20% lower than predicted values, indicating the need for larger heat and mass exchangers to achieve the expected system level performance. The gas-fired burner configuration required for this heat pump is governed by the water heater envelope, desorber geometry and process requirements, coupled with emissions requirements. Parametric CFD analyses were conducted to estimate the impact of chamber design on burner performance, and revealed a beneficial recirculation pattern within the combustion chamber that was strongly influenced by chamber height. Emission reductions depended on chamber diameter, and prototype burners with smaller outer diameter fabricated based on these designs met emission targets.

Because of the performance of the power generation equipment is almost perfect, how to integrate the thermally-activated technologies and use the waste heat deeply are a critical issue for CCHP (Combined cooling heating and power) system. According to the characteristics of a typical end user’s demands, a CCHP system with the flue gas and geothermal energy is proposed. The system is composed of an internal combustion engine, a soil source absorption heat pump driven by the flue gas, and other assistant facilities, such as pumps, fans, and end user devices. In the winter, the flue gas is used to drive absorption heat pump to recover the waste heat of the soil source and the condensation heat of the flue gas simultaneously, and in the summer, the waste heat of the flue gas is used to drive absorption heat pump to cooling, and the heat sink is the soil. In the paper, the energy analysis of the system is done. Compared with the conventional CCHP system, the operation cost is lowered greatly and the increased investment could be returned within one year. It is show that the system is the efficient integration of clean energy, renewable energy, the discharge of the flue gas could be reduced to below 30°C, and the water steam could be catch to avoid the white smoke of the stack.

As an energy-saving and environmentally friendly technology, the combined cooling heating and power system (CCHP) had been applied in the field of heating and air conditioning. Chinese researchers recently designed a CCHP system with the condensation heat recovery of the flue gas, which composed of a gas-powered internal combustion engine (ICE), an exhaust-gas-driven absorption heat pump (AHP), a flue gas condensation heat exchanger (CHE), and other assistant facilities, such as pumps, fans, and end user devices. The system was built and operated in 2011. We tested the parameters of the system on the heating and cooling status from the ICE to the CHE, including the temperature and flux of water, the inlet and outlet parameters of different facilities, and the performance of different facilities for a typical operation status. Based on the test results, the overall COP of the system in the heating and cooling mode was computed, and the energy efficiency level was analyzed. The results indicated that the energy utilization efficiency is about 94% on the heating status, and the energy utilization efficiency is about 84% on the cooling status. These results could serve as a reference for designing or evaluating the CCHP systems.