scholarly journals Design and Transient Analysis of a Natural Gas-Assisted Solar LCPV/T Trigeneration System

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5930
Author(s):  
Yang Liu ◽  
Han Yue ◽  
Na Wang ◽  
Heng Zhang ◽  
Haiping Chen
Keyword(s):  
Natural Gas ◽  
Heat Pump ◽  
High Efficiency ◽  
Coefficient Of Performance ◽  
Cooling Mode ◽  
Energy Supply System ◽  
Simulation Performance ◽  
Temperature Heat ◽  
Maximum Coefficient ◽  
Transient System

This paper proposes a natural gas assisted solar low-concentrating photovoltaic/thermal trigeneration (NG-LCPV/T-TG) system. This novel system simultaneously provides electrical, thermal and cooling energy to the user. The design and dynamic simulation performance of the NG-LCPV/T-TG system is completed using Transient System Simulation (TRNSYS) software. The results show that the system can satisfy the requirements of the cooling and heating load. The proposed system maintains the experimental room temperature at about 25 °C under the cooling mode, at about 20 °C under the heating mode. The electrical and thermal energy produced by the low-concentrating photovoltaic/thermal (LCPV/T) system are 3819 kWh and 18,374 kWh. Meanwhile, the maximum coefficient of performance (COP) of the low temperature heat pump (LHP), high temperature heat pump (HHP) and chiller are 5, 2.2 and 0.6, respectively. This proposed system realizes the coupling of natural gas and solar energy in a building. In summary, this trigeneration system is feasible and it promotes the implementation of building integrated high-efficiency energy supply system.

scholarly journals Efficiency Evaluation of the Ejector Cooling Cycle using a New Generation of HFO/HCFO Refrigerant as a R134a Replacement

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2136 ◽  
Author(s):  
Bartosz Gil ◽  
Jacek Kasperski
Keyword(s):  
High Efficiency ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Evaporation And Condensation ◽  
Wide Range ◽  
Theoretical Investigations ◽  
Maximum Coefficient ◽  
C 30 ◽  
New Generation ◽  
And Control

Theoretical investigations of the ejector refrigeration system using hydrofluoroolefins (HFOs) and hydrochlorofluoroolefin (HCFO) refrigerants are presented and discussed. A comparative study for eight olefins and R134a as the reference fluid was made on the basis of a one-dimensional model. To facilitate and extend the possibility of comparing our results, three different levels of evaporation and condensation temperature were adopted. The generator temperature for each refrigerant was changed in the range from 60 °C to the critical temperature for a given substance. The performed analysis shown that hydrofluoroolefins obtain a high efficiency of the ejector system at low primary vapor temperatures. For the three analyzed sets of evaporation and condensation temperatures (te and tc equal to 0 °C/25 °C, 6 °C/30 °C, and 9 °C/40 °C) the maximum Coefficient of Performance (COP) was 0.35, 0.365, and 0.22, respectively. The best performance was received for HFO-1243zf and HFO-1234ze(E). However, they do not allow operation in a wide range of generator temperatures, and, therefore, it is necessary to correctly select and control the operating parameters of the ejector.

Secondary Fluids for GAX Absorption Heat Pump

2003 ◽  
Author(s):  
G. Anand ◽  
C. B. Panchal ◽  
D. C. Erickson
Keyword(s):  
Los Angeles ◽  
Natural Gas ◽  
Heat Pump ◽  
Performance Model ◽  
Coefficient Of Performance ◽  
Pumping Power ◽  
Ambient Conditions ◽  
Absorption Heat Pump ◽  
Heating And Cooling ◽  
Secondary Fluid

The gas-fired Generator-Absorber heat eXchanger (GAX) heat pump is being considered for space conditioning in residential and light commercial applications. In order to meet the national building codes for ammonia absorption heat pumps, a secondary fluid is used to interface with the air-coils. Proper choice of a secondary fluid maximizes the economic advantage of the GAX heat pump. The secondary fluid transfers the heating and cooling loads from the absorption heat pump to and from outdoor and indoor air-coils. The physical properties of secondary fluids influence the heat transfer performance in the heat-exchange equipment and hence the effective lift, thereby determining the cycle coefficient of performance (COP). Additionally, the pumping power for each fluid varies depending on the density and viscosity at operating temperatures. The variation in cycle COP and pumping power as a result of fluid properties is ultimately manifested as changes in electric and natural-gas cost. An analysis was carried out to evaluate six secondary fluids for a GAX absorption heat pump. A performance model was developed to simulate the secondary-fluid flow loops and the absorption heat pump. The utility costs for heating and cooling were determined for a typical building. The effects of ambient conditions and local utility rates were determined by modeling the annual utility costs in four cities: Atlanta, Chicago, Los Angeles, and New York. These four cities provided wide variations in heating and cooling requirements, and utility rates for natural gas and electricity. The results from this study provide a basis for selecting secondary fluids for heat pumping in different locations.

Application Study of Newly Developed Turbo Heat Pump for 130 Degrees Celsius Water for an Industrial Process

2011 ◽  
Author(s):  
Shuichi Umezawa ◽  
Haruo Amari ◽  
Hiroyuki Shimada ◽  
Takashi Matsuhisa ◽  
Ryo Fukushima ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Low Temperature ◽  
Heat Source ◽  
Heat Pump ◽  
High Efficiency ◽  
Industrial Process ◽  
Application Study ◽  
Hot Air ◽  
Heat Demand ◽  
Temperature Heat

This paper reports application study of newly developed turbo heat pump for 130 degrees Celsius (°C) water for an industrial process in an actual factory. The heat pump is characterized by high efficiency and large heat output, by using a state-of-the-art turbo compressor. The heat pump requires a low temperature heat source in order to achieve high efficiency. The heat demand is for several drying furnaces in the factory, which requires producing hot air of 120 °C. The heat exchanger was designed to produce the hot air. Experiments were conducted to confirm the performance of the heat exchanger under a reduced size of the heat exchanger. Low temperature heat sources are from both exhaust gas of the drying furnaces and that of an annealing furnace. The heat exchangers were also designed to recover heat of the exhaust gas from the two types of furnace. A thermal storage tank was prepared for the low temperature heat source, and for adjusting the time difference between the heat demand and the low temperature heat source. The size of the tank was determined by considering the schedule of furnaces operations. As a result of the present study, it was confirmed that the heat pump was able to satisfy the present heat demand while retaining high efficiency. Primary energy consumption and CO2 emission of the heat pump were calculated on the basis of the present results in order to compare them with those of the boilers.

scholarly journals A comparative study of sustainable industrial heat supply based on economic and thermodynamic factors

2018 ◽  
Vol 68 (3) ◽  
pp. 145-156
Author(s):  
Magdalena Wolf ◽  
Tobias Pröll
Keyword(s):  
Natural Gas ◽  
Heat Supply ◽  
Combined Cycle ◽  
Electricity Price ◽  
Coefficient Of Performance ◽  
Economic Conditions ◽  
Saturated Steam ◽  
Heat Recovery Boiler ◽  
Electricity Prices ◽  
Temperature Heat

SummaryThree different process types of heat supply for industrial production processes requiring low temperature heat at 140°C are analyzed and compared with each other. The thermodynamic and economic efficiency of a gas turbine process with a heat recovery boiler (GT), a gas and steam turbine combined cycle process with a back-pressure turbine (GT-CC) and a high temperature heat pump (HTHP) system recovering waste heat from humid exhaust air between 90°C and 50°C are assessed based on energy flows, exergy flows and costs of heat provided as 4 bar (abs) saturated steam. The economic analysis bases on the comparison of the consumption-related costs of heat, the capital-related costs of heat and the operation-related costs of heat. The payback-times are calculated for different HTHP investment cost levels (1000 EUR/kWQ, 750 EUR/kWQ, 500 EUR/kWQ and 250 EUR/kWQ). To evaluate the effects of fluctuating energy costs, a sensitivity analysis with varying gas and electricity prices has been carried out.The results show that the HTHP system, even with modest performance assumptions, has a higher exergetic efficiency than the GT or the GT-CC process. For the consumption-related costs, the economic calculation shows that the operation of a HTHP, working with a coefficient of performance (COP) of four and for a natural gas price of 25 EUR/MWh, is the cheapest way of heat production as long as the electricity price is lower than 45 EUR/MWh. An electricity price above 45 EUR/MWh makes a GT-CC process more favorable. For the period from January 2013 until June 2016, the total costs of heat and the payback times, based on real gas and electricity prices from the EEX, are calculated and analyzed. For overall cost-optimized heat supply, the results show that the share of heat provided by the HTHP system varies between 45% and 76% between January 2013 and June 2016. Especially in 2013 and 2014, the economic conditions for operating heat pumps were very good. Since October 2015, the natural gas prices have seen a decrease and the economic conditions shifted again favoring the industrial heat supply with combined heat and power systems.

scholarly journals A comparative study of industrial heat supply based on second-law analysis and operating costs

2018 ◽  
Vol 22 (5) ◽  
pp. 2203-2213 ◽  
Author(s):  
Magdalena Wolf ◽  
Thomas Detzlhofer ◽  
Tobias Proll
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Heat Pump ◽  
Heat Supply ◽  
Combined Cycle ◽  
Coefficient Of Performance ◽  
Saturated Steam ◽  
Heat Recovery Boiler ◽  
Pump System ◽  
Heat Pump System

In this paper, the thermodynamic and economic efficiency of three different heat supply processes are compared, based on exergy flows and costs of heat. A gas turbine process with a heat recovery boiler, a gas and steam turbine combined cycle process and a high temperature heat pump system recovering waste heat are analysed. The aim is to provide heat as 4 bar(abs) saturated steam. The economic analysis bases on the comparison of the consumption-related costs of heat, the capital-related costs of heat, and the operation-related costs of heat. The results show that the heat pump system has higher exergetic efficiency than the gas turbine or the gas turbine combined cycle process. For the consumption related costs, the economic calculation shows that the operation of a heat pump, working with a coefficient of performance of four and for a natural gas price of 25 ?/MWh, is the cheapest way of heat production as long as the electricity price is lower than 45 ?/MWh. For the period from January 2013 until June 2016 the total costs of heat, based on real gas and electricity prices from the European Energy Exchange, are calculated and analysed. The results show that the share of heat provided by the heat pump system varies between 45% and 76%. Especially in 2013 and 2014, the economic conditions for operating heat pumps were very good. Since October 2015 the natural gas prices have seen a decrease which favours industrial heat supply with combined heat and power systems.

Smart Heating System for Old Buildings - An Approach to the Decentralized Use of Renewable Energies

2016 ◽  
Vol 19 ◽  
pp. 20-26 ◽  
Author(s):  
Moritz Hein ◽  
Ralf Stöber ◽  
Gerhard Fischerauer ◽  
Johannes Bürner ◽  
Jörg Franke ◽  
...  
Keyword(s):  
Heat Pump ◽  
Electromagnetic Compatibility ◽  
Heating System ◽  
Renewable Energies ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Radiant Heating ◽  
Central Heating ◽  
Maximum Coefficient ◽  
Planar Carbon

The central heating units of buildings are typically replaced every 20 to 30 years. There exists a variety of solutions for fuel-and gas-based units, but it would be advantageous to be able to use renewable energies. This would become possible by the combination of planar carbon-fiber-based infrared (IR) radiant heating foils with a heat pump providing hot water. The main goal of our proposed overall control strategy is to increase the energy efficiency while maintaining the thermal comfort for the residents. We examined the electromagnetic compatibility of the heating foils and simulated the relative contributions of the amount of energy provided by the heat pump and by the heating foils to obtain a maximum coefficient of performance for the combined heating system.

scholarly journals Impact of Carbon Pricing on Energy Cost Savings Resulting from Installation of Gas-Fired Absorption Heat Pump at A Library Building in Ontario

Proceedings ◽  
2019 ◽  
Vol 23 (1) ◽  
pp. 2 ◽  
Author(s):  
Altamash Ahmad Baig ◽  
Alan S. Fung
Keyword(s):  
Natural Gas ◽  
Heat Pump ◽  
Energy Cost ◽  
Energy Savings ◽  
Cost Savings ◽  
Conventional Heating ◽  
Positive Energy ◽  
Cooling Mode ◽  
Carbon Pricing ◽  
Absorption Heat Pump

This paper presents the results of analyzing the potential benefits of a natural gas-fired absorption heat pump (GAHP) for a library building in Ontario in terms of energy savings, fuel cost savings, and reduction in greenhouse gas emissions. Simulation model for the library building was created in eQUEST and calibrated using the energy consumption data from the 2012–2014. The results for energy savings were analyzed to include the effect of implementation of carbon pricing. It was concluded that because of implementation of carbon pricing, the replacement of conventional heating equipment with more efficient gas-fired heat pump would increase the monetary value of the savings achieved from reduced natural gas consumption, due to increased price of natural gas. Furthermore, due to the longer heating season in Canada and the relatively higher price of electricity compared to natural gas the gas-fired heat pump can potentially achieve positive energy cost savings when operated in both heating and cooling mode even after implementation of carbon pricing.

scholarly journals Performance Results of a Solar Adsorption Cooling and Heating Unit

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1630 ◽  
Author(s):  
Tryfon C. Roumpedakis ◽  
Salvatore Vasta ◽  
Alessio Sapienza ◽  
George Kallis ◽  
Sotirios Karellas ◽  
...  
Keyword(s):  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Solar Thermal Energy ◽  
Cooling Mode ◽  
Heating Unit ◽  
Adsorption Chiller ◽  
Maximum Coefficient ◽  
Solar Powered ◽  
Evacuated Tube Collectors ◽  
Performance Results

The high environmental impact of conventional methods of cooling and heating increased the need for renewable energy deployment for covering thermal loads. Toward that direction, the proposed system aims at offering an efficient solar powered alternative, coupling a zeolite–water adsorption chiller with a conventional vapor compression cycle. The system is designed to operate under intermittent heat supply of low-temperature solar thermal energy (<90 °C) provided by evacuated tube collectors. A prototype was developed and tested in cooling mode operation. The results from the testing of separate components showed that the adsorption chiller was operating efficiently, achieving a maximum coefficient of performance (COP) of 0.65. With respect to the combined performance of the system, evaluated on a typical week of summer in Athens, the maximum reported COP was approximately 0.575, mainly due to the lower driving temperatures with a range of 75 °C. The corresponding mean energy efficiency ratio (EER) obtained was 5.8.

scholarly journals Гибридные режимы работы термоэлектрических модулей

2022 ◽  
Vol 56 (1) ◽  
pp. 13
Author(s):  
И.А. Драбкин ◽  
Л.Б. Ершова
Keyword(s):  
Cooling Capacity ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Large Temperature ◽  
Hybrid Mode ◽  
Cooling Mode ◽  
Thermoelectric Coolers ◽  
General Cooling ◽  
Maximum Coefficient

It is suggested that thermoelectric coolers designing should not be limited to the extreme modes of their operation. In some cases, it is convenient to use the so called hybrid modes - a combination of the extreme mode of maximum coefficient of performance for large temperature differences and a general cooling mode for small ones. The proposed hybrid mode makes it possible to control the cooling capacity of the module and not to confine this value to that under the extreme operating conditions, the maximum coefficient of performance in particular.

Sign in / Sign up

Export Citation Format

Share Document