scholarly journals Energy and exergy analysis of combined cooling and power system using variable mode adsorption chiller

2021 ◽  
Vol 294 ◽  
pp. 03002
Author(s):  
Ahmad A. Alsarayreh ◽  
Ayman Al-Maaitah ◽  
Menwer Attarakih ◽  
Hans-Jörg Bart
Keyword(s):  
Ambient Temperature ◽  
Waste Heat ◽  
Exergy Efficiency ◽  
Single Stage ◽  
Ambient Conditions ◽  
Adsorption Chiller ◽  
Energy And Exergy ◽  
Variable Mode ◽  
Combined Cooling ◽  
Mass Recovery

Adsorption cooling is a promising technology to recover low-temperature waste heat from a diesel genset. In this paper, an advanced adsorption chiller working in variable mode is proposed for the combined cooling and power cycle (CCP) to recover waste heat from the water jacket in the diesel genset. The chiller works on three modes based on the ambient temperature for better heat utilization. In this study, three modes were investigated: single-stage cycle mode, short-duration, and medium-duration mass recovery modes. The results show that the energy and exergy efficiency for a single-stage cycle mode is higher at an ambient temperature lower than 35 °C . In comparison, the mass recovery mode has a higher energy and exergy efficiency at an ambient temperature higher than 35 °C. The annual energy and exergy efficiency for the CCP was investigated when the chiller works with variable modes based on the ambient temperature under DUBAI weather conditions as a case study. The results show an improvement of 14.7% and 14% of the energy and exergy efficiency, respectively, for CCP with a variable mode adsorption chiller compared to diesel genset alone. The results also show the CCP with variable mode adsorption chiller has a slight improvement on both energy and exergy efficiency compared to CCP with a single-stage adsorption chiller at the same ambient conditions.

scholarly journals Energy and Exergy Analyses of Adsorption Chiller at Various Recooling-Water and Dead-State Temperatures

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2172
Author(s):  
Ahmad A. Alsarayreh ◽  
Ayman Al-Maaitah ◽  
Menwer Attarakih ◽  
Hans-Jörg Bart
Keyword(s):  
Water Temperature ◽  
Recovery Time ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Adsorption Chiller ◽  
Dead State ◽  
Energy And Exergy ◽  
The Dead ◽  
Exergy Analyses ◽  
Mass Recovery

We conducted energy and exergy analyses of an adsorption chiller to investigate the effect of recooling-water temperatures on the cooling capacity and Coefficient of Performance (COP) with variable cycle modes. We investigated both the effect of the recooling-water temperature and the dead state temperature on the exergy destruction in the chiller components. Our results show that there is an optimum reheat cycle mode for each recooling-water temperature range. For the basic single stage cycle, the exergy destruction is mainly accrued in the desorber (49%), followed by the adsorber (27%), evaporator (13%), condenser (9%), and expansion valve (2%). The exergy destruction for the preheating process is approximately 35% of the total exergy destruction in the desorber. By contrast, the precooling process is almost 58% of the total exergy destruction in the adsorber. The exergy destruction decreases when increasing the recooling-water and the dead state temperatures, while the exergy efficiency increases. Nonetheless, the exergy efficiency decreases with an increase in the recooling-water temperature at fixed dead state temperatures. The effect of the mass recovery time in the reheat cycle on exergy destruction was also investigated, and the results show that the exergy destruction increases when the mass recovery time increases. The exergy destruction in the adsorbent beds was the most sensitive to the increase in mass recovery time.

scholarly journals Performance Analysis of Variable Mode Adsorption Chiller at Different Recooling Water Temperatures

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3871
Author(s):  
Ahmad A. Alsarayreh ◽  
Ayman Al-Maaitah ◽  
Menwer Attarakih ◽  
Hans-Jörg Bart
Keyword(s):  
Experimental Data ◽  
Water Temperature ◽  
Cycle Time ◽  
Single Stage ◽  
Force Model ◽  
Technical Problems ◽  
Cooling Cycle ◽  
Adsorption Chiller ◽  
Variable Mode ◽  
Mass Recovery

Adsorption cooling can recover waste heat at low temperature levels, thereby saving energy and reducing greenhouse gas emissions. An air-cooled adsorption cooling system reduces water consumption and the technical problems associated with wet-cooling systems; however, it is difficult to maintain a constant recooling water temperature using such a system. To overcome this limitation, a variable mode adsorption chiller concept was introduced and investigated in this study. A prototype adsorption chiller was designed and tested experimentally and numerically using the lumped model. Experimental and numerical results showed good agreement and a similar trend. The adsorbent pairs investigated in this chiller consisted of silicoaluminophosphate (SAPO-34)/water. The experimental isotherm data were fitted to the Dubinin–Astakhov (D–A), Freundlich, Hill, and Sun and Chakraborty (S–C) models. The fitted data exhibited satisfactory agreement with the experimental data except with the Freundlich model. In addition, the adsorption kinetics parameters were calculated using a linear driving force model that was fitted to the experimental data with high correlation coefficients. The results show that the kinetics of the adsorption parameters were dependent on the partial pressure ratio. Four cooling cycle modes were investigated: single stage mode and mass recovery modes with duration times of 25%, 50%, and 75% of the cooling cycle time (denoted as short, medium, and long mass recovery, respectively). The cycle time was optimized based on the maximum cooling capacity. The single stage, short mass recovery, and medium mass recovery modes were found to be the optimum modes at lower (<35 °C), medium (35–44 °C), and high (>44 °C) recooling temperatures. Notably, the recooling water temperature profile is very important for assessing and optimizing the suitable working mode.

scholarly journals Energy and Exergy Efficiency Analysis of Fluid Flow and Heat Transfer in Sinter Vertical Cooler

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4522
Author(s):  
Zude Cheng ◽  
Haitao Wang ◽  
Junsheng Feng ◽  
Yongfang Xia ◽  
Hui Dong
Keyword(s):  
Heat Transfer ◽  
Energy Efficiency ◽  
Fluid Flow ◽  
Waste Heat ◽  
Exergy Efficiency ◽  
Inlet Temperature ◽  
Operational Parameters ◽  
Flow And Heat Transfer ◽  
Maximum Value ◽  
Energy And Exergy

In order to fully understand the energy and exergy transfer processes in sinter vertical coolers, a simulation model of the fluid flow and heat transfer in a vertical cooler was established, and energy and exergy efficiency analyses of the gas–solid heat transfer in a vertical cooler were conducted in detail. Based on the calculation method of the whole working condition, the suitable operational parameters of the vertical cooler were obtained by setting the net exergy efficiency in the vertical cooler as the indicator function. The results show that both the quantity of sinter waste heat recovery (SWHR) and energy efficiency increased as the air flow rate (AFR) increased, and they decreased as the air inlet temperature (AIT) increased. The increase in the sinter inlet temperature (SIT) resulted in an increase in the quantity of SWHR and a decrease in energy efficiency. The air net exergy had the maximum value as the AFR increased, and it only increased monotonically as the SIT and AIT increased. The net exergy efficiency reached the maximum value as the AFR and AIT increased, and the increase in the SIT only resulted in a decrease in the net exergy efficiency. When the sinter annual production of a 360 m2 sintering machine was taken as the processing capacity of the vertical cooler, the suitable operational parameters of the vertical cooler were 190 kg/s for the AFR, and 353 K for the AIT.

scholarly journals Energy and Exergy Analyses of Tube Banks in Waste Heat Recovery Applications

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2094 ◽  
Author(s):  
Mustafa Erguvan ◽  
David MacPhee
Keyword(s):  
Energy Efficiency ◽  
Reynolds Number ◽  
Heat Recovery ◽  
Waste Heat ◽  
Cross Flow ◽  
Exergy Efficiency ◽  
Circular Cylinders ◽  
Published Data ◽  
Energy And Exergy ◽  
Exergy Analyses

In this study, energy and exergy analyses have been investigated numerically for unsteady cross-flow over heated circular cylinders. Numerous simulations were conducted varying the number of inline tubes, inlet velocity, dimensionless pitch ratios and Reynolds number. Heat leakage into the domain is modeled as a source term. Numerical results compare favorably to published data in terms of Nusselt number and pressure drop. It was found that the energy efficiency varies between 72% and 98% for all cases, and viscous dissipation has a very low effect on the energy efficiency for low Reynolds number cases. The exergy efficiency ranges from 40–64%, and the entropy generation due to heat transfer was found to have a significant effect on exergy efficiency. The results suggest that exergy efficiency can be maximized by choosing specific pitch ratios for various Reynolds numbers. The results could be useful in designing more efficient heat recovery systems, especially for low temperature applications.

Study on solar/waste heat driven multi-bed adsorption chiller with mass recovery

2007 ◽  
Vol 32 (3) ◽  
pp. 365-381 ◽  
Author(s):  
M.Z.I. Khan ◽  
B.B. Saha ◽  
K.C.A. Alam ◽  
A. Akisawa ◽  
T. Kashiwagi
Keyword(s):  
Waste Heat ◽  
Adsorption Chiller ◽  
Mass Recovery

scholarly journals Optimization of Solar CCHP Systems with Collector Enhanced by Porous Media and Nanofluid

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Navid Tonekaboni ◽  
Mahdi Feizbahr ◽  
Nima Tonekaboni ◽  
Guang-Jun Jiang ◽  
Hong-Xia Chen
Keyword(s):  
Porous Media ◽  
Maximum Energy ◽  
Exergy Efficiency ◽  
Solar Collectors ◽  
Efficiency Enhancement ◽  
Optimal Amount ◽  
Solar Systems ◽  
Energy And Exergy ◽  
Low Efficiency ◽  
Combined Cooling

The low efficiency of solar collectors can be mentioned as one of the problems in solar combined cooling, heating, and power (CCHP) cycles. For improving solar systems, nanofluid and porous media are used in solar collectors. One of the advantages of using porous media and nanoparticles is to absorb more energy under the same conditions. In this research, a solar combined cooling, heating, and power (SCCHP) system has been optimized by porous media and nanofluid for generating electricity, cooling, and heating of a 600 m2 building in a warm and dry region with average solar radiation of Ib = 820 w/m2 in Iran. In this paper, the optimal amount of nanofluid in porous materials has been calculated to the extent that no sediment is formed. In this study, solar collectors were enhanced with copper porous media (95% porosity) and CuO and Al2O3 nanofluids. 0.1%–0.6% of the nanofluids were added to water as working fluids; it is found that 0.5% of the nanofluids lead to the highest energy and exergy efficiency enhancement in solar collectors and SCCHP systems. Maximum energy and exergy efficiency of parabolic thermal collector (PTC) riches in this study are 74.19% and 32.6%, respectively. Figure 1 can be mentioned as a graphical abstract for accurately describing the cycle of solar CCHP.

scholarly journals Modelling of energy and exergy analysis of ORC integrated systems in terms of sustainability by applying artificial neural network

2020 ◽  
Author(s):  
Zafer Utlu ◽  
Mert Tolon ◽  
Arif Karabuga
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Solar Energy ◽  
Ambient Temperature ◽  
Exergy Analysis ◽  
Energy System ◽  
Exergy Efficiency ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Artificial Neural

Abstract The present study focuses on the organic Rankine cycle (ORC) integrated into an evacuated tube heat pipe (ETHP), whose systems are an alternative solar energy system to low-efficiency planary collectors. In this work, a detailed thermodynamic and artificial neural network (ANN) analysis was conducted to evaluate the solar energy system. One of the key parameters of sustainable approaches focused on exergy efficiency is application of thermal engineering. In addition to this, sustainable engineering approaches nowadays are a necessity for improving the efficiency of all of the engineering research areas. For this reason, the ANN model is used to forecast different types of energy efficiency problems in thermodynamic literature. The examined system consists of two main parts such as the ETHP system and the ORC system used for thermal energy production. With this system, it is aimed to evaluate energy and exergy analysis results by the ANN method in the case of integrating the ORC system to ETHP, which is one of the planar collectors suitable for the roofs of the buildings. Within the scope of this study, the exergy efficiency was evaluated on the developed ANN algorithm. The effect rates of parameters such as pressure, temperature and ambient temperature affecting the exergy efficiency of ORC integrated ETHP were calculated. Ambient temperature was found to be the most influential parameter on exergy efficiency. The exergy efficiency of the whole system has been calculated as ~23.39%. The most suitable BPNN architecture for this case study is recurrent networks with dampened feedback (Jordan–Elman nets). The success rate of the developed BPNN model is 95.4%.

scholarly journals Exergy Analysis of Advanced Adsorption Cooling Cycles

Entropy ◽  
2020 ◽  
Vol 22 (10) ◽  
pp. 1082
Author(s):  
Ngoc Vi Cao ◽  
Xuan Quang Duong ◽  
Woo Su Lee ◽  
Moon Yong Park ◽  
Seung Soo Lee ◽  
...  
Keyword(s):  
Recovery Time ◽  
Heat Recovery ◽  
Exergy Analysis ◽  
Exergy Efficiency ◽  
Recovery Cycle ◽  
Adsorption Chiller ◽  
Advanced Cycles ◽  
Heat And Mass Recovery ◽  
Exergy Losses ◽  
Mass Recovery

This study conducted an exergy analysis of advanced adsorption cooling cycles. The possible exergy losses were divided into internal losses and external losses, and the exergy losses of each process in three advanced cycles: a mass recovery cycle, heat recovery cycle and combined heat and mass recovery cycle were calculated. A transient two-dimensional numerical model was used to solve the heat and mass transfer kinetics. The exergy destruction of each component and process in a finned tube type, silica gel/water working paired-adsorption chiller was estimated. The results showed that external loss was significantly reduced at the expense of internal loss. The mass recovery cycle reduced the total loss to 60.95 kJ/kg, which is −2.76% lower than the basic cycle. In the heat recovery cycle, exergy efficiency was significantly enhanced to 23.20%. The optimum value was 0.1248 at a heat recovery time of 60 s. The combined heat and mass recovery cycle resulted in an 11.30% enhancement in exergy efficiency, compared to the heat recovery cycle. The enhancement was much clearer when compared to the basic cycle, with 37.12%. The observed dependency on heat recovery time and heating temperature was similar to that observed for individual mass recovery and heat recovery cycles.

Energy and Exergy Analysis of a Hybrid Solar System in Terms of Thermal Energy Production and Cooling

2017 ◽  
Author(s):  
I. P. Koronaki ◽  
M. T. Nitsas ◽  
E. G. Papoutsis
Keyword(s):  
Solar System ◽  
Thermal Energy ◽  
Energy Savings ◽  
Cooling System ◽  
Operating Cost ◽  
Cooling Capacity ◽  
Exergy Efficiency ◽  
Cooling Power ◽  
Adsorption Chiller ◽  
Energy And Exergy

In this study a hybrid solar system, already available in the Laboratory of Applied Thermodynamics at NTUA is examined in terms of thermal energy and cooling power production. The system is installed in Athens, Greece and it comprises of two types of solar collectors, namely one series of CPC-PVT (Compound Parabolic Concentrator-Photovoltaic Thermal) collectors and one series of ETC (Evacuated Tube Collector), one indirect water buffer with an intermediate heat exchanger and a commercial zeolite adsorption chiller (LTC vario, Invensor). Simulations are carried out in order to estimate the energy and exergy efficiency of the system, the produced cooling capacity as well as the thermal energy stored in the buffer. Moreover, the performance of the chiller is evaluated for various months by determining the Cooling Capacity and COP, both solar and thermal. In order to determine, if the proposed solar cooling system performs better than a conventional that covers the same load, the primary energy savings and the reduction of CO2 emissions are calculated. The operating cost savings are also estimated. The simulation results show that the under study systems can indeed work sufficiently when the specific types and surface of collectors are considered. In specific, the system exhibits an average COP of 0.5 for the under study period while its solar exergy efficiency (nearly 2.5%) leads to the conclusion that the system, especially the collectors, can undergo an optimization process.

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