Primary Energy Ratio Research Articles

The multi-goal optimal analysis of stand-alone gas engine heat pump system with energy storage (ESGEHP) system

Gas-engine driven heat pump could avoid energy loss in the process of generation, transmission and distribution, and effectively reduce the electric power load at the peak time in summer. In the present study, a novel stand-alone gas engine heat pump system with energy storage is put forward, which combined with the energy storage system and the autonomous power supply system. The annual performance optimization model of the gas engine heat pump system with energy storage system is proposed, which is calculated based on APSO algorithm. The simulation results were well agreed with experimental data, the average difference is 8.9%, 9.63% and 21.7% for the annual primary energy ratio of heating, cooling, transitional season, respectively. Based on the simulation results, the autonomous generating capacity E and the speed of engine n have high effect on the objective function, and the ratio of electricity to heat/cool/domestic hot water should be no greater than 0.1. The annual primary energy ratio of the gas engine heat pump system with energy storage system in heating, cooling and transitional season was increased by 6.11, 19.11% and 34.83% compared with the gas-engine driven heat pump system, respectively. The gas engine heat pump system with energy storage system can be used indifferent climate regions and buildings, which could provide a more stable work mode and higher annual primary energy ratio than the gas-engine driven heat pump system with a little energy loss.

Exploring heating performance of gas engine heat pump with heat recovery

In order to evaluate the heating performance of gas engine heat pump (GEHP) for air-conditioning and hot water supply, a test facility was developed and experiments were performed over a wide range of engine speed (1400-2600 r/min), ambient air temperature (2.4-17.8 °C) and condenser water inlet temperature (30-50 °C). The results show that as engine speed increases from 1400 r/min to 2600 r/min, the total heating capacity and energy consumption increase by about 30% and 89%, respectively; while the heat pump coefficient of performance (COP) and system primary energy ratio (PER) decrease by 44% and 31%, respectively. With the increase of ambient air temperature from 2.4 °C to 17.8 °C, the heat pump COP and system PER increase by 32% and 19%, respectively. Moreover, the heat pump COP and system PER decrease by 27% and 15%, respectively, when the condenser water inlet temperature changes from 30 °C to 50 °C. So, it is obvious that the effect of engine speed on the performance is more significant than the effects of ambient air temperature and condenser water inlet temperature.

Energy, exergy and environmental analysis of a hybrid combined cooling heating and power system utilizing biomass and solar energy

A hybrid combined cooling heating and power (CCHP) system driven by biomass and solar energy is proposed, and their complementarity to enhance the system’s energy efficiency is analyzed and shown. The CCHP system is primarily composed of a biomass gasification sub-system, solar evacuated collector, internal combustion engine and dual-source powered mixed-effect absorption chiller. The product gas produced by the gasifier drives the internal combustion engine to generate power, and the waste heat after generation is utilized to produce cooling and heating with the collected heat from the solar collectors. Under the design conditions, the thermodynamic performances under variable external conditions and energy ratios are investigated and analyzed. The results indicate that the primary energy ratio and the exergy efficiency are 57.9% and 16.1%, respectively, and the carbon emission reduction ratio is about 95.7%, at the design condition. The complementarity analysis between the biomass and solar energy shows that the biomass subsystem makes a greater contribution to the total system primary energy ratio and exergy efficiency than the contributions from the solar subsystem, and the participation of solar energy is conducive to the system emission reduction.

Performance analysis of diesel engine heat pump incorporated with heat recovery

This paper presents experimental study of diesel engine heat pump (DEHP) system to find potential as retrofit technology in off-gas or weak electricity network area to replace existing gas/oil/electric heating system in domestic sector. Test set-up of diesel engine driven water-to-water heat pump system was built which included heat recovery arrangement from the engine coolant & exhaust gas. The system was designed to meet typical house heating demand in Northern Ireland. Performance of DEHP was evaluated to meet house-heating demand at different flow temperature (35, 45, 55 & 65°C), a typical requirement of underfloor space heating, medium/high temperature radiators and domestic hot water. The performance was evaluated against four-evaporator water inlet temperature (0, 5, 10 & 15°C) and at three different engine speed 1600, 2000 & 2400rpm. Experiment results were analysed in terms of heating/cooling capacity, heat recovery, total heat output, primary energy ratio (PER), isentropic efficiency, etc. Test results showed that DEHP is able to meet house-heating demand with help of heat recovery with reduced system size. Heat recovery contributed in a range of 22–39% in total heat output. It is possible to achieve high flow temperature in a range of 74°C with help of heat recovery. Overall system PER varied in a range of 0.93–1.33. Speed increment and flow temperature has significant impact on heat recovery, total heat output and PER. A case scenario with different flow temperature to match house-heating demand has been presented to show working potential with different heat distribution system. In addition, DEHP shows good potential to save primary energy consumption and CO2 emissions, a helpful technology to achieve national emission reduction target.

Experimental study on cooling performance and energy saving of gas engine-driven heat pump system with evaporative condenser

The gas engine-driven heat pump (GEHP) is widely utilized to the process of cooling, heating or food drying. Aiming at improving the coefficient of performance (COP), primary energy ratio (PER) and energy saving of GEHP, a GEHP system with evaporative condenser was developed and the cooling performances were experimented over a wide range of ambient air temperature (30–36°C), evaporative condenser air velocity (2.2–3.9m/s) and gas engine speeds (1200–2200rpm). Experimental results showed that the cooling capacity and PER of the GEHP system with evaporative condenser increased as the increasing of evaporative condenser air velocity and decreasing of ambient air temperature. The increasing and decreasing extents of cooling capacity and PER were 12.1%, 4.8% and 8.2%, 9.0%, respectively. However, the gas engine energy consumption and gas engine waste heat decreased with the increasing of evaporative air velocity and decreasing of ambient air temperature. Meanwhile, the cooling capacity, gas engine energy consumption, gas engine waste heat increased with increasing of gas engine speed, and the increase amplitude was 75.64%, 153.2% and 153.3%, respectively. The maximum value of PER of GEHP system with evaporative condenser was 1.55, and the waste heat recovered from gas engine was more than 55% of gas engine energy consumption.The energy saving and emission saving of the GEHP with evaporative condenser were also analyzed, the PER savings of GEHP system with evaporative condenser compared to conventional air-cooled condenser were 28.1%. Furthermore, compared to the GEHP with air-cooled condenser, the primary energy saving and CO2 emissions saving of GHEP with evaporative condenser were 16.3% and 8.8%. The results displayed an excellent energy-saving feature.

Comparing World Economic and Net Energy Metrics, Part 2: Total Economy Expenditure Perspective

We translate between energetic and economic metrics that characterize the role of energy in the economy. Specifically, we estimate monetary expenditures for the primary energy and net external power ratio (NEPR direct ; NEPR, net external power ratio), a power return ratio of annual energy production divided by annual direct energy inputs within the energy industry. We estimate these on an annualized basis for forty-four countries from 1978 to 2010. Expressed as a fraction of gross domestic product (GDP), f e , GDP , the forty-four country aggregate (composing >90% world GDP) worldwide expenditures on energy decreased from a maximum of 10.3% in 1979 to a minimum of 3.0% in 1998 before increasing to a second peak of 8.1% in 2008. While the global f e , GDP fluctuates significantly, global NEPR direct declined from a value of 34 in 1980 to 17 in 1986 before staying in a range between 14 and 16 from 1991 to 2010. In comparing both of these metrics as ratios of power output over power input, one economic ( f e , GDP - 1 ) and one biophysical (NEPR direct ), we see that when the former divided by the latter is below unity, the world was in a low-growth or recessionary state.

Experimental study on performance of a biogas engine driven air source heat pump system powered by renewable landfill gas

The equipment configuration of a landfill gas (LFG) fueled biogas engine driven air source heat pump system was studied. The process flow for collecting and purifying LFG was analyzed, and the LFG collection and purification method was determined. An experimental apparatus was set up, and the effect of biogas engine speed variation on LFG consumption, exhaust fume temperature of biogas engine, recovered waste heat from exhaust fume and cylinder liner, coefficient of performance (COP) of the heat pump and primary energy ratio (PER) of the system were experimentally tested. The results indicated that LFG consumption and biogas engine exhaust fume temperature increased with biogas engine speed. When the biogas engine operated in the 70%–90% rated speed range, the system heat output and exhaust fume waste heat recovery rate would be relatively higher. In addition, the maximum COP and PER reached 4.2 and 1.4 respectively.

Sensitivity analysis in determining the optimum energy for residential buildings in Polish conditions

The article applies the global costs calculation method with regard to the energy assessment of the selected solutions for the technical equipment of buildings, depending on the purpose and function of the building. The global costs were calculated by means of the net present value method in accordance with the cost-optimal draft regulation. In order to determine the sensitivity of the optimal ratio of primary energy to the adopted initial data, the total cost of the building, which is the sum of the investment and operating costs in the assumed operating period, was analyzed. The procedure takes into account the variability of the thermal envelope of the building, the ventilation requirements and the macroeconomic parameters. Primary energy includes all energy used for heating, ventilation, hot water and auxiliary energy and depends on the adopted macroeconomic parameters.In the region lacking economic stability, such as Eastern Europe, the sensitivity analysis is important for the process of establishing thermal requirements of the building and the energy supplied. In those countries, the economic changes will lead to changes in requirements over time.

Development and field test of a high-temperature heat pump used in crude oil heating

In this paper, a high-temperature heat pump (HTHP) is developed and manufactured to replace the traditional oil-fired boiler heater for crude oil heating. It extracts thermal energy from waste hot water separated from the crude oil to provide high-temperature hot water to heat the crude oil. A prototype of the HTHP system is installed in the Jinzhou oil treatment station in Liaoning, China and the field test is conducted for about 6000 h. A typical 144 h of field testing data is analyzed to evaluate the performance of the designed HTHP system. It is observed that the temperature of hot water provided by the HTHP unit varies from 86 ℃ to 95 ℃ throughout the whole operating period and is sufficient for the crude oil heating (80–90 ℃). The heating capacity and power consumption of the HTHP system varies from 1350 to 1785 kW, and 171 to 197 kW, respectively. The overall system coefficient of performance ranges from 3.5 to 4.4 with an average value of 3.8. Based on the experimental results, a primary energy ratio is introduced to evaluate and compare the economics of the studied HTHP system and oil-fired boiler heater. The comparison shows that the energy consumed by the HTHP unit is only 57% of that consumed by the oil-fired boiler heater. If all traditional oil-fired boiler heaters are replaced by the HTHPs in the Jinzhou oil treatment station, the total yearly energy saving is around 1.12 × 104 tons of equivalent coal which equates to 1.76 × 104 tons of CO2 emissions.

An Analysis of the Primary Energy Consumed by the Re-Liquefaction of Boil-off Gas of LNG Storage Tank

The pressure in liquefied natural gas (LNG) storage tank continues to increase due to the heat transfer from ambient air to low temperature LNG, which raises safety concerns. This research numerically analyzed the energy consumption of the re-liquefaction of BOG using the following four approaches: 1) a Claude cycle driven by electrical motor with the electricity produced by burning coal; 2) a Brayton cycle driven by a gas turbine fuelled by BOG released; 3) a Claude cycle driven by a SI engine fuelled by BOG; 4) using liquefied nitrogen produced in industry. With the efficiencies of the power system derived from industry data, the energy consumed of the re-liquefaction process was explored. The impact of heat transfer coefficient, LNG tank configuration, size, and percentage of LNG stored in tank on the rate of BOG and energy needed for the re-liquefaction of methane vapor were investigated. The primary energy ratio (PER), defined as the ratio of the energy recovered to the energy consumed, was examined and compared. The highest PER was observed using the Claude cycle driven by internal combustion engine fueled with BOG while the lowest PER was observed when BOG was cooled using liquefied nitrogen approach. The data presented in this paper provides the guideline for the management of pressure development in LNG storage tank and the design of accessory LNG storage system capable of re-liquefying the BOG gas to LNG.

Study to examine the potential for solar energy utilization based on the relationship between urban morphology and solar radiation gain on building rooftops and wall surfaces

The possibility of solar energy utilization is discussed based on the relationship between urban morphology and solar radiation gain on building rooftops and wall surfaces. It was found that solar radiation on the rooftops of all the buildings in Osaka is reduced to about 86.3% when shadows of surrounding buildings are considered. It is further reduced to about 78.6% when obstacles on the rooftop are added. Power generation is estimated to be 27.3PJ/year if photovoltaic panels were introduced to all free space on the buildings in Osaka. This corresponds to 1.93 Mt-CO2/year, with the reduction ratio of primary energy and CO2 emission being about 12.4% and 8.5% respectively. Solar heat generation is estimated to be 109.1PJ/year if solar heat collectors were introduced to all free space on the buildings in Osaka. This corresponds to 5.55 Mt-CO2/year, with the reduction ratio of primary energy and CO2 emissions being about 49.6% and 24.3% respectively. The relationship between street characteristics and solar radiation on roofs and walls was analyzed for a typical fine summer day. The ratio of solar radiation on wall, roof, and ground surfaces is 17.5%, 25.7%, and 56.8%, respectively, on an average. In residential and industrial areas, there are few buildings, which experience reduced solar radiation on their roofs due to lower building coverage ratio. However, in the city center and in the residential areas, several buildings experience reduced amount of solar radiation on their roofs due to the effect of shadows by surrounding buildings. In the wide north–south and east–west streets, solar radiation on the walls is not reduced, because the heights of the buildings along the main street are aligned. In the narrow north–south streets, solar radiation on the walls is reduced when the opposite building is higher than the building in question. In the narrow east–west streets, solar radiation on the south side walls is not reduced due to the high solar altitude.

Performance of a combined cooling heating and power system with mid-and-low temperature solar thermal energy and methanol decomposition integration

In this paper, a new distributed energy system that integrates the mid-and-low temperature solar energy thermochemical process and the methanol decomposition is proposed. Through the solar energy receiver/reactor, the energy collected by a parabolic trough concentrator, at 200–300°C, is used to drive the decomposition reaction of the methanol into the synthesis gas, and thus the solar thermal energy is converted to the chemical energy. The chemical energy of the synthesis gas released in the combustion chamber of a micro gas turbine is used to drive the combined cooling heating and power systems. Energy analysis and exergy analysis of the system are implemented to evaluate the feasibility of the proposed system. Under the considerations of the changes of the solar irradiation intensity, the off-design performances of the micro turbine and the variations of the load, the design and off-design thermodynamic performances of the system and the characteristics of the chemical energy storage are numerically studied. Numerical results indicate that the primary energy ratio of the system is 76.40%, and the net solar-electricity conversion rate reaches 22.56%, which is higher than exiting large-scale solar thermal power plants. Owing to the introduction of a the solar thermochemical energy storage in the proposed system, the power generation efficiency is insensitive to the variations of the solar radiation, and thus an efficient and stable utilization approach of the solar thermal energy is achieved at all work condition.

Long term performance of different SAGSHP solutions for residential energy supply in Finland

Abstract The presented paper focuses on different control strategies of a solar assisted ground source heat pump (SAGSHP) for cold climate. Dynamic simulation approach has been used through TRNSYS software. In particular, a SAGSHP solution operating with the strategies suitable for cold climate found in literature, a conventional ground source heat pump (GSHP) solution and a GSHP with solar thermal system only for building heating supply have been compared to the SAGSHP proposed system. The impact of the considered system solutions on seasonal performance factor and primary energy ratio in case of a gas boiler as auxiliary system has been evaluated as a function of the boreholes depth, the conventional solar thermal collector typologies and the size of the solar thermal system. Results have shown that the proposed strategy is effective from a specific borehole depth. Moreover, the solar thermal collector typology has to be selected accordingly to the borehole depth and to the used auxiliary source. Furthermore, the temperature difference between solar collectors and the ground, which has to be exceeded for driving solar heat into it, has to be kept low for system with short borehole in order to drive more heat into the ground and it has to be incremented with the increasing of borehole length, especially for small solar thermal system size when flat plate and evacuated tube solar collector typologies are adopted.

Performance analysis of a solar cooling plant based on a liquid desiccant evaporative cooler

Summer air conditioning represents a growing market in buildings worldwide, with a significant growth rate observed in European commercial and residential buildings. Available heat driven cooling technologies can be used in combination with solar thermal collectors to reduce the load caused by air conditioning on the electric utilities and to reduce the environmental impact. This work reports a performance analysis of an open cycle solar cooling plant. The plant, installed in Northern Italy, is based on a liquid desiccant evaporative cooler coupled with a solar field. Experimental tests run during summer show average primary energy ratio and primary energy saving index of about 1.6 and 30%, respectively. Though this performance is satisfactorily, the regeneration unit always operated near the lower bound of the nominal temperature range. Therefore, optimization of the solar system design could lead to higher performance.

Experimental Study of the Gas Engine Driven Heat Pump with Engine Heat Recovery

Gas engine driven heat pumps (GEHPs) represent one of practical solutions to effectively utilize fossil fuel energy and reduce environmental pollution. In this paper, the performance characteristics of the GEHP were investigated experimentally with engine heat recovery. A GEHP test facility was set up for this purpose. The effects of several important factors including engine speed, ambient temperature, condenser water flow rate, and condenser water inlet temperature on the system performance were studied over a wide range of operating conditions. The results showed that the engine waste heat accounted for about 40–50% of the total heat capacity over the studied operating conditions. It also showed that engine speed and ambient temperature had significant effects on the GEHP performance. The coefficient of performance (COP) and the primary energy ratio (PER) decreased by 14% and 12%, respectively, as engine speed increased from 1400 rpm to 2000 rpm. On the other hand, the COP and PER of the system increased by 22% and 16%, respectively, with the ambient temperature increasing from 3 to 12°C. Furthermore, it was demonstrated that the condenser water flow rate and condenser water inlet temperature had little influence on the COP of the heat pump and the PER of the GEHP system.

ICOPE-15-C128 Research about management mode of Combined Cooling Heating and Power system

Combined Cooling Heating and Power (CCHP) system is a distributed energy system of high efficient and low pollution. The operation and management mode involved should be taken as one of the judgments to measure the economic efficiency of CCHP system. In the paper, a system which takes natural gas as fuel is designed for a vacation village. In the new system, which originally bases on the coal-fired separate energy system, a micro gas turbine is used to provide power and heat is provided with its waste heat exhausted. Considering the benefit of the vacation village, Analyze the system from two different economical perspectives: the nanny support (NS) mode and the self-management (SF) mode. The results indicate that the primary energy ratio of the system designed is 86.2%, which is 10.6% up compared with original one. But maintenance expenses of NS mode is 696 thousand RMB more than original separate energy system. So NS mode is obviously unavailable for self-sustaining users. Therefore, further analyze shows that the nanny style management mode will reduce device's investment recovery period to about 7 years. No matter which method is chosen, policy of the government and benefits of each sides involved should be taken into consideration when designing the system.

Study on Simulation Performance of Solar Energy and Gas Heat Pump for Heating Supply

This paper introduces a new system named solar energy and gas heat pump, based on the solar heat pump system driven by electricity. The study established the models of the system according to the using of TRNSYS and SIMULINK. This paper mainly studies on the performance parameters of the new system, such as evaporation temperature, COP and heating capacity. At the same time, the paper makes a comparison of COP and PER between gas heat pump and solar energy heat pump, solar energy and gas heat pump. The results show that the evaporating temperature increases by 0.84°C when the thermal storage tank temperature increases by 1°C and the condensing temperature increases by 1.46°C when the condenser inlet temperature increases by 1°C. The COP of the new system can reach 4.76 and the primary energy ratio of the system is up to 1.96, which is superior to the other two systems obviously.

Energy-Saving Analysis and Heat Transfer Performance of Wastewater Source Heat Pump

There is a large potential in the heat loss from the urban wastewater. In all kinds of low-grade heat sources, urban wastewater is gradually widely used because of its advantages such as huge quantities, small variation of temperature, warm in winter and cool in summer, etc. By integrating a heat pump to utilize this heat, the wastewater source heat pump (WWSHP), which is a new water reuse and treatment strategy to tackle the water problems of China and to realize the sustainable development, recovers the heat of wastewater. The WWSHP air conditioning system as residential application can reduce the need of energy systems based on fossil fuel for cooling, heating, and hot water's supply purposes. The system's working principle, classification and the wastewater's characteristic parameters were discussed in this paper. And the scheme of using WWSHP system for central air-conditioning compared with other refrigerating and heating equipments was analyzed in detail. The investigation into COP (Coefficient of Performance) and PER (Primary Energy Ratio) was shown in this paper. Among the four kinds of common air conditioning units, when the loads are same respectively, the WWSHP has the most significant energy-saving effect. Furthermore, mechanism of heat transfer enhancement for falling-film evaporation and condensation surface of tubes packed with wire-mesh is also studied in detail. Theoretical simulation will be carried out for the heat transfer process and the flow of falling-film outside horizontal tubes. Improvement of controlling parameters influenced the evaporation and condensation performance, and then led to an increase in the refrigerating quantity and the COP. Consequently, this WWSHP system has its theoretical significance and promising engineering application potentials for the residential refrigerating and air-conditioning system using low-temperature waste heat source.

Design and modeling of 1–10 MWe liquefied natural gas-fueled combined cooling, heating and power plants for building applications

Decentralized, liquefied natural gas-fueled, trigeneration plants are considered as alternatives to centralized, electricity-only generating power plants to improve efficiency and minimize running costs. The proposed system is analyzed in terms of efficiency and cost. Electrical power is generated with a gas turbine, while waste heat is recovered and utilized effectively to cover heating and cooling needs for buildings located in the vicinity of the plant. The high quality of cooling energy carried in the LNG fluid is used to cool the air supply to the air compressor. Waste heat is recovered with heat exchangers to generate useful heating in the winter period, while in the summer period an integrated double-effect absorption chiller converts waste heat to useful cooling. For the base system (10MWe), net electrical efficiency is up to 36.5%, while the primary energy ratio reaches 90%. The payback period for the base system is 4 years, for a lifecycle cost of 221.6 million euros and an investment cost of 13 million euros. The base system can satisfy the needs of more than 21,000 average households, while an equivalent conventional system can only satisfy the needs of 12,000 average households.

Thermodynamic performance assessment of CCHP system driven by different composition gas

In order to facilitate sustainable solutions in megacities, waste-to-energy study of municipal solid waste handling is conducted including anaerobic digestion and thermal cracking, together with power generation technologies and the utilization of residual waste heat. In this paper, performance of CCHP (Combined Cooling Heating and Power) system, which is driven by different composition gases that the main components are CH4, H2, CO, SH2, C2H4, etc. is evaluated. The related parameters of the system, such as PER (primary energy ratio) of CCHP, exergy efficiency of CCHP ηex, the efficiency of gas engine η, and COP (Coefficient of Performance) of absorption refrigeration, were analyzed in different compression ratio of gas engine and under off-design conditions. The results indicated that the different composition gases had evident effect on the performance of CCHP. For the waste handling and waste-to-energy in metropolis, the gas input to CCHP system form anaerobic digestion and thermal cracking (pyrolysis) should be determined by considering all kinds of factors, such as cost of gas, efficiency of gas engine, cooling and heat load.