scholarly journals Theoretical Study for an Adsorption Refrigerator

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Abdulghani M. Ramadan
Keyword(s):  
Adsorption Capacity ◽  
Waste Heat ◽  
Cooling System ◽  
Operating Conditions ◽  
Equilibrium Adsorption ◽  
Design Parameters ◽  
Low Grade ◽  
Equilibrium Pressure ◽  
Study Results ◽  
Equilibrium Adsorption Capacity

Adsorption cooling technology is one of the effective means to convert low grade thermal energy in to effective cooling, which improves energy efficiency and lowers environmental pollution. The main objective of this study is to investigate the thermal performance of an adsorption refrigerator theoretically. The working adsorbent/adsorbate pair used is Granular Activated Carbon, GAC/R134a pa*ir. The effect of different design parameters and operating conditions on the system performance is studied and interpreted.Some assumptions and approximations are also considered. A computer program is written using Matlab. Results show that the equilibrium adsorption capacity is highly affected by the driving temperature and equilibrium pressure. Increasing equilibrium pressure leads to a corresponding increase in the equilibrium adsorption capacity whereas it is value is decreased as the driving temperature increases. Moreover, increasing the driving and evaporator temperatures raise the values of the Specific Cooling Effect (SCE) andCoefficient of Performance (COP). The maximum values of SCE and COP are 60 KJ/kg and 0.4 corresponding to driving and evaporator temperatures of 100 oC and 20 oC respectively. However, increasing the condenser temperature leads to a remarked decrease in SCE and COP of the cooling system. SCE and COP values are 32 KJ/kg and 0.22 at driving and condenser temperatures of 100 oC and 40 oC respectively. When comparing the present study results with literature, there is a good agreement in general. It is clear that the adsorption cooling system can be driven effectively by low grade heat sources such as, solar energy, waste heat energy, geothermal energy…etc.

A Parametric Examination of the Factors Affecting the Performance of a Diffusion Absorption Refrigeration System

2021 ◽  
pp. 1-38
Author(s):  
Noman Yousuf ◽  
Timothy Anderson ◽  
Roy Nates
Keyword(s):  
Waste Heat ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Low Grade ◽  
Absorption Refrigeration ◽  
Factors Affecting ◽  
Thermally Driven ◽  
Mass Flowrate ◽  
Diffusion Absorption

Abstract Despite being identified nearly a century ago, the diffusion absorption refrigeration (DAR) cycle has received relatively little attention. One of the strongest attractions of the DAR cycle lies in the fact that it is thermally driven and does not require high value work. This makes it a prime candidate for harnessing low grade heat from solar collectors, or the waste heat from stationary generators, to produce cooling. However, to realize the benefits of the DAR cycle, there is a need to develop an improved understanding of how design parameters influence its performance. In this vein, this work developed a new parametric model that can be used to examine the performance of the DAR cycle for a range of operating conditions. The results showed that the cycle's performance was particularly sensitive to several factors: the rate of heat added and the temperature of the generator, the effectiveness of the gas and solution heat exchangers, the mass flowrate of the refrigerant and the type of the working fluid. It was shown that can deliver good performance at low generator temperatures if the refrigerant mass fraction in the strong solution is made as high as possible. Moreover, it was shown that a H2O-LiBr working pair could be useful for achieving cooling at low generator temperatures.

Design and Analysis of a High Power Density, Low Temperature Waste Heat Recovery System Using an Oil-Free Turboalternator

2010 ◽  
Author(s):  
James F. Walton ◽  
Andrew Hunsberger ◽  
Hooshang Heshmat
Keyword(s):  
Output Power ◽  
Waste Heat ◽  
Maximum Output Power ◽  
Output Power Level ◽  
Working Fluid ◽  
Prototype System ◽  
Low Grade ◽  
Maximum Output ◽  
Test Results ◽  
Study Results

In this paper the authors will present the design and preliminary test results for a distributed electric generating system that uses renewable energy source for economical load-following and peak-shaving capability in an oil-free, high-speed micro-turboalternator system using compliant foil bearings and a permanent magnet alternator. Test results achieved with the prototype system operating to full speed and under power generating mode will be presented. A comparison between predicted and measured electrical output will also be presented up to a power generating level of 25 kWe at approximately 55,000 rpm. The excellent correlation between design and test provides the basis for scale up to larger power levels. Based upon the turboalternator test results a thermodynamic cycle analysis of a system using low grade waste heat water at approximately 100 C will be reviewed. The tradeoff study results for a series of environmentally friendly refrigerant working fluids will also be presented including sensitivity to vaporization and condensing temperatures. Based on the cycle and pinch point analyses predicted maximum output power was determined. Finally a preliminary turbine design for the selected R134a working fluid was completed. The results of this study show that a net output power level of greater than 40 kW is possible for approximately 240 l/m flow of water at 100C is possible.

Meanline Analysis and CFD Study of a Radial Inflow Turbine With Vaneless Distributor for Low Temperature Organic Rankine Cycle

2020 ◽  
Author(s):  
M. Deligant ◽  
S. Braccio ◽  
T. Capurso ◽  
F. Fornarelli ◽  
M. Torresi ◽  
...  
Keyword(s):  
Energy Demand ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Low Grade ◽  
Heat Sources ◽  
Turbine Wheel ◽  
Good Efficiency ◽  
Low Grade Heat

Abstract The Organic Rankine Cycle (ORC) allows the conversion of low-grade heat sources into electricity. Although this technology is not new, the increase in energy demand and the need to reduce CO2 emissions create new opportunities to harvest low grade heat sources such as waste heat. Radial turbines have a simple construction, they are robust and they are not very sensitive to geometry inaccuracies. Most of the radial inflow turbines used for ORC application feature a vaned nozzle ensuring the appropriate distribution angle at the rotor inlet. In this work, no nozzle is considered but only the vaneless gap (distributor). This configuration, without any vaned nozzle, is supposed to be more flexible under varying operating conditions with respect to fixed vanes and to maintain a good efficiency at off-design. This paper presents a performance analysis carried out by means of two approaches: a combination of meanline loss models enhanced with real gas fluid properties and 3D CFD computations, taking into account the entire turbomachine including the scroll housing, the vaneless gap, the turbine wheel and the axial discharge pipe. A detailed analysis of the flow field through the turbomachine is carried out, both under design and off design conditions, with a particular focus on the entropy field in order to evaluate the loss distribution between the scroll housing, the vaneless gap and the turbine wheel.

Applicability Research on Evaporative Cooling Technology in Hunan Province

2014 ◽  
Vol 1070-1072 ◽  
pp. 1679-1683
Author(s):  
Qin Ouyang ◽  
Guang Xiao Kou ◽  
Min Ouyang
Keyword(s):  
Energy Consumption ◽  
Air Conditioning ◽  
Waste Heat ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Hunan Province ◽  
Design Parameters ◽  
Climate Conditions ◽  
Energy Saving Potential ◽  
Evaporative Cooling System

According to the climate conditions of Hunan province and the design parameters related to air conditioning, the energy consumption and the related characteristics of the liquid desiccant evaporative cooling system (LDECS) are compared with primary return air conditioning system. The results show that energy consumption of LDECS can be decreased by 11.78% compared to the primary return air system. LDECS has a certain degree of energy saving potential in Hunan province, especially when waste heat is available.

Adsorption Properties of Pr3+ and Nd3+ Using Silica Grafted with Larch Tannin

2012 ◽  
Vol 550-553 ◽  
pp. 1561-1565 ◽  
Author(s):  
Tian Tian Xu ◽  
Chu Rui Huang ◽  
Yuan Yuan Luo ◽  
Qiang Du ◽  
Shi Lin Zhao
Keyword(s):  
Adsorption Capacity ◽  
Ph Value ◽  
Adsorption Properties ◽  
Equilibrium Adsorption ◽  
Dynamics Model ◽  
Adsorption Capacities ◽  
Optimum Ph ◽  
Pseudo Second Order ◽  
Equilibrium Adsorption Capacity ◽  
Order Rate Equation

The new adsorption material was prepared by grafting the larch tannin onto aminated silica beads with the glutaraldehyde as the cross-linking agent. The adsorption properties of Pr3+and Nd3+on the new adsorbent material in aqueous solution were investigated. The results showed that the equilibrium adsorption capacities of this adsorbent to Pr3+, Nd3+were 402.12mg/g, 305.43mg/g at 303K when the initial concentrations of each ions were 442.7mg/L, 432.6mg/L, respectively and the pH value was 5.5; the maximum adsorption quantities of each ions were 576.34mg/g, 497.02mg/g at 303K when the initial concentrations of each ions were 704.5mg/L, 721.0mg/L, respectively and the pH value was 5.5. The effect of pH value was significant to the equilibrium adsorption capacity, the optimum pH values of this material to Pr3+and Nd3+were both 5.5; while the effect of the temperature was not obvious to the equilibrium adsorption capacity. The adsorption thermodynamics meet Freundlich equation, and the adsorption kinetics data of this adsorbent to Pr3+, Nd3+fitted with the pseudo-second-order rate equation dynamics model.

scholarly journals Techno-economic analysis of waste heat recovery by inverted Brayton cycle applied to an LNG-fuelled transport truck

2021 ◽  
Vol 238 ◽  
pp. 10008
Author(s):  
Kirill Abrosimov ◽  
Federica Sciacchitano ◽  
Gianluca Pasini ◽  
Andrea Baccioli ◽  
Aldo Bischi ◽  
...  
Keyword(s):  
Economic Analysis ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Fossil Fuels ◽  
Waste Heat ◽  
Cooling System ◽  
Rapid Development ◽  
Economic Assessment ◽  
Design Parameters ◽  
Brayton Cycle

Aiming for the better environmental and economic performance of traditional engines, waste heat recovery (WHR) technologies are actively studied to find their most beneficial applications. In this work, the inverted Brayton cycle (IBC) is investigated as a potential WHR solution for liquefied natural gas (LNG) fuelled transport truck. LNG being one of the less polluting fossil fuels is widely spreading nowadays in different industries due to the rapid development of the LNG supply chain in the world. LNG-fuelled cargo transportation follows this prevailing trend. Based on the overexpansion of flue gases to subatmospheric pressure, inverted Brayton cycle, in turn, is considered a prospective technology of WHR and techno-economic analysis of IBC in several configurations on-board of a heavy transport truck have been assessed. IBC is integrated into the engine cooling system in the basic layout, and additionally, it incorporates LNG regasification process in advanced configurations. Power balance based on Aspen Hysys model enables to perform system optimisation and gives preliminary design parameters of the system components. Cost function approach provides the basis for a preliminary economic assessment of the layouts. Although the system shows fuel economy of maximum about 2.1 %, analysis revealed the necessity to continue the search for better technical solutions in IBC-based systems to make them economically attractive due to high cost of installed equipment.

scholarly journals Waste Heat Driven Multi-Ejector Cooling Systems: Optimization of Design at Partial Load; Seasonal Performance and Cost Evaluation

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5663
Author(s):  
Luca Viscito ◽  
Gianluca Lillo ◽  
Giovanni Napoli ◽  
Alfonso William Mauro
Keyword(s):  
Waste Heat ◽  
Cooling System ◽  
Electric Energy ◽  
Cost Evaluation ◽  
Low Grade ◽  
Ambient Temperatures ◽  
Partial Load ◽  
Seasonal Performance ◽  
Ejector System ◽  
Break Even Point

In this paper, a seasonal performance analysis of a hybrid ejector cooling system is carried-out, by considering a multi-ejector pack as expansion device. A 20 kW ejector-based chiller was sized to obtain the optimal tradeoff between performance and investment costs. The seasonal performance of the proposed solution was then evaluated through a dynamic simulation able to obtain the performance of the designed chiller with variable ambient temperatures for three different reference climates. The optimized multi-ejector system required three or four ejectors for any reference climate and was able to enhance the system performance at partial load, with a significant increase (up to 107%) of the seasonal energy efficiency ratio. The proposed system was then compared to conventional cooling technologies supplied by electric energy (electrical chillers EHP) or low-grade heat sources (absorption chillers AHP) by considering the total costs for a lifetime of 20 years and electric energy-specific costs for domestic applications from 0.10 to 0.50 €/kWhel. The optimized multi-ejector cooling system presented a significant convenience with respect to both conventional technologies. For warmer climates and with high electricity costs, the minimum lifetime for the multi-ejector system to achieve the economic break-even point could be as low as 1.9 years.

scholarly journals Recovery of Low-Grade Heat (Heat Waste) from a Cogeneration Unit for Woodchips Drying: Energy and Economic Analyses

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 501 ◽  
Author(s):  
Tilia Dahou ◽  
Patrick Dutournié ◽  
Lionel Limousy ◽  
Simona Bennici ◽  
Nicolas Perea
Keyword(s):  
Waste Heat ◽  
Point Of View ◽  
Operating Conditions ◽  
Low Grade ◽  
Drying Time ◽  
Financial Gain ◽  
Return Water ◽  
Economic Analyses ◽  
The Right ◽  
Low Grade Heat

The aim of this paper is to improve the operating share of a biomass cogeneration unit by using unavoidable heat waste heat recovered from a district network heating used for drying woody biomass’ return water (law-grade temperature heat). The optimal operating conditions of a drying unit added to the system were estimated from an energy and a financial point of view, applying four objective functions (drying time, energy consumption, energy balance, and financial performance of the cogeneration unit). An experimental design methodology used heat for the implementation of these functions and to obtain an operating chart. Numerical modelling was performed to develop a simulation tool able to illustrate the unsteady operations able to take into account the available waste heat. Surprisingly, the model shows that the right strategy to increase the financial gain is to produce more warm water than necessary and to consequently dispose higher quantities of unavoidable heat in the network’s return water, which heat up the drying air at a higher temperature. This result contrasts with the current approaches of setting-up cogeneration units that are based on the minimization of the heat production.

Thermo-economic Assessment, and Multi-objective Optimization of an Innovatively Designed District Cooling System in Saudi Arabia

2021 ◽  
pp. 1-29
Author(s):  
Ali Alsagri
Keyword(s):  
Saudi Arabia ◽  
Waste Heat ◽  
Cooling System ◽  
Economic Assessment ◽  
Optimization Techniques ◽  
Operating Conditions ◽  
Peak Shaving ◽  
Assessment Index ◽  
Economic Analyses

Abstract The experience of leading countries in distributed energy systems (e.g., Scandinavian countries) shows that district cooling systems are highly beneficial techno-economic-environmentally by facilitating the use of waste heat resources, solar energy, etc., for cold supply at large scales. This study proposes the optimal development of a novel district cooling design utilizing the exhaust waste heat of an energy plant in a case study in Saudi Arabia. The optimal configuration of the hybrid system, the sizing of its components, and operating conditions of them are found using multiobjective optimization techniques based on the genetic algorithm method and a creative performance assessment index. Then, the feasibility of this optimized proposal is investigated through comprehensive thermodynamic and economic analyses. The results show that a district cooling system can surely cope with the harsh climate condition of the case study and provide the required interior comfort conditions. The energy and exergy efficiencies of the system can be as high as 62% and 53% using an absorption chiller utilizing a power plant's waste heat along with a storage tank for peak shaving. The levelized cost of cooling of the system can be 28 USD/MWh, by which the payback period will be only 8 years.

Oscillating Heat Pipes for Waste Heat Recovery in HVAC Systems

2015 ◽  
Author(s):  
Govinda Mahajan ◽  
Heejin Cho ◽  
Scott M. Thompson ◽  
Harrison Rupp ◽  
Kevin Muse
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Heat Pipes ◽  
Hvac Systems ◽  
Operating Conditions ◽  
Working Fluid ◽  
Low Grade ◽  
Potential Cost

Oscillating heat pipes (OHPs) were experimentally assessed as a passive-type heat transfer device for air-to-air heat exchange in a typical Heating Ventilation & Air conditioning system (HVAC) with adjacent air streams at different temperatures. The objective is to utilize, otherwise wasted thermal energy to pre-heat or pre-cool air in order to reduce the payload on HVAC systems, thus reducing energy consumption. OHPs can achieve effective thermal conductivities on-the-order of 10,000 W/m-K via no internal wicking structure and hence can perform aforementioned heat transfer task while providing an aerodynamic form factor. A unique working fluid with limited research inside OHPs, but with properties desirable for low grade heat fluxes, i.e. n-pentane with 70 % fill ratio, was chosen as the working fluid to achieve maximum heat transfer. Aerodynamic performance, in terms of pressure drop, was evaluated and juxtaposed with heat transfer gain/loss. The OHP thermal performance and total heat transfer for hot-environment HVAC operation was benchmarked with an empty/evacuated OHP with same overall dimensions. Results indicate that the current, atypically-long OHP is fully-capable of operating in the air-to-air convection mode for waste heat recovery for typical HVAC operating conditions. Since the OHP is passive, cost effective, and relatively aerodynamic (no fins were used), the potential cost savings for its integration into HVAC systems can be significant.

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