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1. A block matrix formulation for efficient g-function construction

Author:
Dusseault, Bernard; Pasquier, Philippe; Marcotte, Denis
Source:
Renewable energy 2018 v.121 pp. 249-260
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; algorithms; equations; models; renewable energy sources;     Show all 5 Subjects
Abstract:
... A compact block matrix formulation allowing fast construction of the g-function of a ground heat exchanger is presented. This new formulation is nor sequential nor iterative, doesn't require use of Laplace or Fourier transform and provides a g-function by solving a single system of linear equations assembled in a block matrix system. A method to accelerate the integration of the finite-line source ...
DOI:
10.1016/j.renene.2017.12.092

2. A comparative study of power optimization in low-temperature geothermal heat source driven R125 transcritical cycle and HFC organic Rankine cycles

Author:
Baik, Young-Jin; Kim, Minsung; Chang, Ki-Chang; Lee, Young-Soo; Yoon, Hyung-Kee
Source:
Renewable energy 2013 v.54 pp. 78-84
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; heat; hydrofluorocarbons; power plants; renewable energy sources; temperature; vapors;     Show all 7 Subjects
Abstract:
... In order to compare the power output of an R125 transcritical cycle with that of HFC subcritical ORCs for a low-temperature geothermal heat source of about 100 °C, an R125 transcritical cycle and subcritical ORCs using R134a, R245fa and R152a were optimized for power output by a simulation method. In contrast to previous studies, to fairly compare the power of different cycles, power optimizations ...
DOI:
10.1016/j.renene.2012.08.055

3. Adsorbent working pairs for solar thermal energy storage in buildings

Author:
Frazzica, Andrea; Freni, Angelo
Source:
Renewable energy 2017 v.110 pp. 87-94
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; activated carbon; adsorbents; adsorption; ammonia; buildings; desorption; ethanol; heat; methanol; silica gel; solar collectors; solar thermal energy; temperature; working conditions; zeolites;     Show all 16 Subjects
Abstract:
... In this study, the thermodynamic analysis of several adsorption working pairs for adsorption heat storage applications at domestic level is presented. The selected working pairs employ different working fluids (i.e. water, ethanol, ammonia, methanol) and different adsorbent materials such as classical zeolites, silica gels, alumino-phosphates, composite sorbents and activated carbons. The simulati ...
DOI:
10.1016/j.renene.2016.09.047

4. Adsorptive transformation and storage of renewable heat: Review of current trends in adsorption dynamics

Author:
Aristov, Yuri I.
Source:
Renewable energy 2017 v.110 pp. 105-114
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; adsorbents; adsorption; desorption; heat; mass transfer; renewable energy sources; solar radiation; temperature; vapor pressure; winter;     Show all 11 Subjects
Abstract:
... The main shortage of emerging technology of adsorptive transformation and storage (ATS) of heat is a low specific power that leads to large-size units poorly competitive so far with common compression systems. Significant intensification of heat and mass transfer in ATS units would allow an overcoming of this drawback. This is especially urgent for transformations driven by renewable heat sources ...
DOI:
10.1016/j.renene.2016.06.055

5. A 3-field earth-heat-exchange system for a school building in Imola, Italy: Monitoring results

Author:
Chiesa, Giacomo; Simonetti, Marco; Grosso, Mario
Source:
Renewable energy 2014 v.62 pp. 563-570
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; air temperature; climate; energy; heat; monitoring; pipes; relative humidity; renewable energy sources; summer; winter; Italy;     Show all 12 Subjects
Abstract:
... The present study reports the results of a 12-month-long monitoring campaign of an earth-to-air horizontal heat exchanger (EAHX) system in a school complex in Imola, Italy. With more than 2 km of buried pipes, it represents one of the biggest Italian applications of this technology. Considerable differences between inlet and outlet air temperature have been noticed both in winter and in summer. Ai ...
DOI:
10.1016/j.renene.2013.08.020

6. Air source thermoelectric heat pump for simultaneous cold air delivery and hot water supply: Full modeling and performance evaluation

Author:
Cai, Yang; Zhang, Dong-Dong; Liu, Di; Zhao, Fu-Yun; Wang, Han-Qing
Source:
Renewable energy 2019 v.130 pp. 968-981
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; air; air temperature; cold; coolers; energy; heat pumps; mass flow; mathematical models; renewable energy sources; specific heat; thermal conductivity; water supply; water temperature;     Show all 14 Subjects
Abstract:
... An air-source thermoelectric heat pump (AS-THP) system is proposed in the present work, and it actively exploits ambient air source energy serving for cold air delivery and hot water supply simultaneously. A mathematical model, combining thermoelectric theory and the effectiveness-number of transfer units (ε-NTU), is firstly conducted to predict the performance of AS-THP system. Subsequently, the ...
DOI:
10.1016/j.renene.2018.07.007

7. A modified three-dimensional numerical model for predicting the short-time-step performance of borehole ground heat exchangers

Author:
Lee, C.K.
Source:
Renewable energy 2016 v.87 pp. 618-627
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; capacitance; mathematical models; prediction; renewable energy sources; temperature;     Show all 6 Subjects
Abstract:
... A modified three-dimensional numerical model for the borehole ground heat exchangers was proposed which took into account the effect of grout thermal capacitance and fluid circulation period inside the U-tube in a short-time-step analysis. The present model was validated by experimental data from others. It was found that the fluid temperature along the U-tube changed abruptly at the interface bet ...
DOI:
10.1016/j.renene.2015.10.052

8. Analysis and performance assessment of a novel ORC based multi-generation system for power, distilled water and heat

Author:
Yari, Mortaza; Ariyanfar, Leyli; Aghdam, Ebrahim Abdi
Source:
Renewable energy 2018 v.119 pp. 262-281
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; condensers; desalination; energy; heat production; octane; renewable energy sources; temperature; water flow;     Show all 9 Subjects
Abstract:
... In this paper, the coupling of a Humidification-Dehumidification Desalination (HDD) with an Organic Rankine Cycle (ORC) as a multi-generation system is proposed in two scenarios to generate power, distilled water and heat. The system is investigated from thermodynamic and economic viewpoints, and for achieving the best results, four organic fluids are examined in the ORC. In the first scenario, th ...
DOI:
10.1016/j.renene.2017.12.021

9. Analysis of optimization in an OTEC plant using organic Rankine cycle

Author:
Yang, Min-Hsiung; Yeh, Rong-Hua
Source:
Renewable energy 2014 v.68 pp. 25-34
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; cold; energy conversion; evaporation; heat transfer; renewable energy sources; seawater; temperature; thermal energy;     Show all 9 Subjects
Abstract:
... This study quantified the effects of evaporation temperature, condensation temperature, and the inlet- and outlet-temperature differences of deep cold seawater and warm seawater on the performance of an ocean thermal energy conversion (OTEC) plant using an organic Rankine cycle (ORC), and also investigated the optimal operations required for the performance. A finite-temperature-difference heat tr ...
DOI:
10.1016/j.renene.2014.01.029

10. Analysis of the effect of eccentricity and operational parameters in PCM-filled single-pass shell and tube heat exchangers

Author:
Pahamli, Younes; Hosseini, Mohammad J.; Ranjbar, Ali A.; Bahrampoury, Rasool
Source:
Renewable energy 2016 v.97 pp. 344-357
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; algorithms; convection; energy; enthalpy; equations; heat transfer; mass flow; melting; models; momentum; porosity; renewable energy sources; temperature; thermal properties;     Show all 15 Subjects
Abstract:
... In the present study, melting behavior of RT50 as a phase change material in a shell and tube heat exchanger is considered. Therefore the effects of parameters including a geometrical property (eccentricity) and flow specifications (mass flow rate and inlet temperature of heat transfer fluid) on different decisive parameters of the PCM are investigated. The selected parameters which are critical f ...
DOI:
10.1016/j.renene.2016.05.090

11. Analysis on Al2O3/water nanofluid flow in a channel by inserting corrugated/perforated fins for solar heating heat exchangers

Author:
Khoshvaght-Aliabadi, M.; Tatari, M.; Salami, M.
Source:
Renewable energy 2018 v.115 pp. 1099-1108
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; geometry; heat transfer; heat transfer coefficient; nanoparticles; renewable energy sources;     Show all 6 Subjects
Abstract:
... Improving the efficiency is a crucial issue to introduce renewable energy as a commercial success. In the current experimental study, the hydrothermal performance of corrugated/perforated fins (CPFs) is investigation for use in plate heat exchangers as heat exchange devise in the active solar heating system. Water and Al2O3/water nanofluid (NF) are applied as working fluid. The considered factors ...
DOI:
10.1016/j.renene.2017.08.092

12. Analysis on the transient heat transfer process inside and outside the borehole for a vertical U-tube ground heat exchanger under short-term heat storage

Author:
Dai, L.H.; Shang, Y.; Li, X.L.; Li, S.F.
Source:
Renewable energy 2016 v.87 pp. 1121-1129
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; heat transfer; models; renewable energy sources; soil temperature; storage time;     Show all 6 Subjects
Abstract:
... A three-dimensional unsteady model is established to study the heat transfer performance for a vertical U-tube ground heat exchanger (GHE). The transient heat transfer process between the inside and outside of the borehole under short-term heat storage is analyzed. The results indicate that the soil temperature field in the depth direction at the center section is distributed in a “narrow belt sha ...
DOI:
10.1016/j.renene.2015.08.034

13. An average fluid temperature to estimate borehole thermal resistance of ground heat exchanger

Author:
Du, Ciyuan; Chen, Youming
Source:
Renewable energy 2011 v.36 no.6 pp. 1880-1885
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; heat tolerance; models; renewable energy sources; temperature;     Show all 5 Subjects
Abstract:
... Analysis of borehole thermal resistance is important for the standard sizing of ground heat exchanger (GHE). In this paper, a p-linear dimensionless average fluid temperature is proposed to estimate borehole thermal resistance. A p-linear dimensionless fluid temperature and p-linear dimensionless average fluid temperature are introduced, and the p-linear dimensionless fluid temperature is compared ...
DOI:
10.1016/j.renene.2010.10.033

14. A network-based methodology for the simulation of borehole heat storage systems

Author:
Lazzarotto, Alberto
Source:
Renewable energy 2014 v.62 pp. 265-275
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; heat; renewable energy sources; thermal energy;     Show all 4 Subjects
Abstract:
... The optimization of strategies to operate borehole thermal energy storage systems can play an important role for the exploitation of this technology. Available tools utilized for the design of borehole fields don't consider these aspects in the calculation. For this reason a network-based methodology which gives a sufficient level of detail to describe different system operation strategies has bee ...
DOI:
10.1016/j.renene.2013.07.020

15. An evaluation and model of the Chinese Kang system to improve indoor thermal comfort in northeast rural China – Part-1: Model development

Author:
(John) Zhai, Zhiqiang; Yates, Andrew Porter; Duanmu, Lin; Wang, Zongshan
Source:
Renewable energy 2015 v.84 pp. 3-11
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; biomass; energy; energy use and consumption; equations; heat; models; renewable energy sources; rural areas; winter; China;     Show all 11 Subjects
Abstract:
... In the rural area of northern China, residents often use a traditional stove-Kang system to heat their homes, which is an effective way of using locally-produced biomass to solve the energy and environment problems. However, many of these homes are not heated sufficiently during the winter months. The current system is inefficient and requires high levels of fuel consumption. This paper researches ...
DOI:
10.1016/j.renene.2015.06.003

16. An evaluation and model of the Chinese Kang system to improve indoor thermal comfort in northeast rural China – Part-2: Result analysis

Author:
Zhai, Zhiqiang John; Yates, Andrew Porter; Duanmu, Lin; Wang, Zongshan
Source:
Renewable energy 2015 v.84 pp. 12-21
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; economic analysis; model validation; models; renewable energy sources; China;     Show all 6 Subjects
Abstract:
... The part-2 provides the calibration and validation of the model backbone against the field experimental data. The paper evaluates the simulation results from a myriad of scenarios on their technical ability to increase domestic comfort. Additionally, input from local communities was used to assess rural residents' heating needs and their acceptability of possible solutions. An economic analysis wa ...
DOI:
10.1016/j.renene.2015.06.002

17. A new approach to estimating temperature fields around a group of vertical ground heat exchangers in two-dimensional analyses

Author:
Sailer, Eleonora; Taborda, David M.G.; Zdravković, Lidija
Source:
Renewable energy 2018 v.118 pp. 579-590
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; buildings; finite element analysis; geometry; heat transfer; models; renewable energy sources; soil temperature; urban areas;     Show all 9 Subjects
Abstract:
... Vertical ground heat exchangers (VHEs), in the form of either Borehole Heat Exchanger (BHE) or thermo-active piles, are increasingly being deployed to provide low cost and sustainable heating and cooling to buildings. These are often installed within densely built urban environments, where adjacent foundation systems and underground structures can be affected by soil temperature changes induced by ...
DOI:
10.1016/j.renene.2017.11.035

18. A new 1D analytical model for investigating the long term heat transfer rate of a borehole ground heat exchanger by Green's function method

Author:
Dehghan B., Babak; Kukrer, Ergin
Source:
Renewable energy 2017 v.108 pp. 615-621
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; heat pumps; heat transfer; models; pipes; polyethylene; prediction; renewable energy sources; temperature;     Show all 9 Subjects
Abstract:
... In ground source heat pump (GSHP) applications, long term performance prediction of a borehole is an important issue since performance of a borehole ground heat exchanger decreases by the life time of the system. Therefore, it is important to find a reliable method determining the long term performance of a borehole. In this study, a new 1D analytical expression for heat transfer rate (HTR) per un ...
DOI:
10.1016/j.renene.2016.11.002

19. A new RC and g-function hybrid model to simulate vertical ground heat exchangers

Author:
Maestre, Ismael Rodríguez; Gallero, Francisco Javier González; Gómez, Pascual Álvarez; Pérez-Lombard, Luis
Source:
Renewable energy 2015 v.78 pp. 631-642
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; equations; fluid mechanics; heat flow; heat transfer; prediction; renewable energy sources; simulation models; temperature;     Show all 9 Subjects
Abstract:
... This paper presents a new hybrid two-dimensional model to simulate single U-tube ground heat exchangers based on the use of the electrical analogy to model heat transfer within the borehole and thermal response factors (short and long time-step g-functions) to estimate heat flow to the surrounding ground. Unlike other similar models, heat transfer equations are discretized only within the borehole ...
DOI:
10.1016/j.renene.2015.01.045

20. An experimental study of a heat pipe evacuated tube solar dryer with heat recovery system

Author:
Daghigh, Roonak; Shafieian, Abdellah
Source:
Renewable energy 2016 v.96 pp. 872-880
ISSN:
0960-1481
Subject:
heat exchangers,   etc   ; air; drying; energy intake; equations; heat recovery; regression analysis; solar energy; weather;     Show all 9 Subjects
Abstract:
... The current study designed, constructed and experimentally evaluated a heat-pipe evacuated tube solar dryer with heat a recovery system in which water was used as working and recovery fluid in the solar and dryer loops, respectively, and air was used as intermediate fluid in the dryer section. The heat recovery system was used to enhance the overall efficiency of the system and to make maximum use ...
DOI:
10.1016/j.renene.2016.05.025