Experimental Study on a New Small-Scale Absorption System: Response Surface and Inverse Analyses

2021 ◽  
pp. 1-41
Author(s):  
Gaurav Singh ◽  
Ranjan Das
Keyword(s):  
Response Surface ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Load ◽  
Driving Factors ◽  
Hot Water ◽  
Small Scale ◽  
Absorption System ◽  
Multi Objective

Abstract In this paper, a new small-scale lithium bromide (LiBr)-water absorption system consisting water-cooled evaporator and air-cooled condenser is experimentally studied. For compactness, water-cooled heat exchangers for evaporator, absorber and generator are made helical-coiled type, whereas, based on the water availability and load requirements, condenser is air-cooled. Accurate empirical correlations for thermal load and evaporator temperature against system driving factors concerning a have been reported. Thereafter, response surface analysis of the developed performance parameters are studied with respect to LiBr concentration, temperature of generator and mass flow rate of hot water. Using experimental data, estimation of overall heat transfer coefficient (U) and its variation with system driving factors is quantified. The error margin between theoretical and actual pressure loss is limited within 5 %. Next, a multi-objective inverse analysis of the developed system is done to simultaneously retrieve the required LiBr concentration, mass flow rate of hot water, and vapor generator temperature to derive a desired cooling performance demand from the system. The obtained U values for all the components are found to be in line with the standard data. The physics related to salt concentration and generator temperature in governing U values are reported. Apart from the developed correlations, it can be established that the necessary operational parameters can be predicted by the present multi-objective inverse method to meet the necessary thermal load and temperature demands within an accuracy level of 6 % and 5 %, respectively.

scholarly journals Thermal Characteristics Analysis on Multi- Heat Pipe Induced Heat Exchanger

2019 ◽  
Vol 9 (2S2) ◽  
pp. 143-147 ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Pipe ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cold Water ◽  
Hot Water ◽  
Working Fluid ◽  
Physical Parameters

In this investigation of multi heat pipe induced in heat exchanger shows the developments in heat transfer is to improve the efficiency of heat exchangers. Water is used as a heat transfer fluid and acetone is used as a working fluid. Rotameter is set to measure the flow rate of cold water and hot water. To maintain the parameter as experimental setup. Then set the mass flow rate of hot water as 40 LPH, 60LPH, 80 LPH, 100LPH, 120 LPH and mass flow rate of cold water as 20 LPH, 30 LPH, 40 LPH, 50 LPH, and 60 LPH. Then 40 C, 45 ºC, 50 ºC, 55 C, 60 ºC are the temperatures of hot water at inlet are maintained. To find some various physical parameters of Qc , hc , Re ,, Pr , Rth. The maximum effectiveness of the investigation obtained from condition of Thi 60 C, Tci 32 C and 100 LPH mhi, 60 LPH mci the maximum effectiveness attained as 57.25. Then the mhi as 100 LPH, mci as 60 LPH and Thi at 40 C as 37.6%. It shows the effectiveness get increased about 34.3 to the maximum conditions.

scholarly journals Simulation and Optimization of Municipal Solid Waste Combustion: A Case Study of a Fixed Bed Incinerator

2020 ◽  
pp. 5-19
Author(s):  
Arthur M. Omari ◽  
John P. John ◽  
Baraka Kichonge
Keyword(s):  
Municipal Solid Waste ◽  
Solid Waste ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Fixed Bed ◽  
Small Scale ◽  
Waste Incinerator ◽  
Simulation And Optimization

In this study, a Computational Fluid Dynamics (CFD) technique was used to develop a model for the simulation and flow conditions of the incinerator. The CFD technique are based on subdividing the volume of interest, i.e., the combustion chamber (or other parts of the plant) into a grid of elementary volumes. The relevant equations of conservation (mass, momentum, energy) are then applied to each of those elements, after defining all inputs, outputs and boundary conditions. The resulting system is then integrated from start to finish, after introducing momentum, mass and heat transfer. The objective of the study was to evaluate and optimize the performance of locally available incinerators in Tanzania. The small scale municipal solid waste incinerator modelling was done by using a fluent solver. The case study of the existing incinerator at a Bagamoyo hospital in Tanzania was used as a model and the obtained values were compared with simulated results and other publications for validation. The design optimization using CFD techniques to predict the performance of incinerator showed the deviation of input air by 14%, the mass flow rate by 26.5%, the mass fraction of carbon dioxide by 10.4% and slight deviation of nitrogen dioxide and carbon monoxide. The study suggested removing the ash during the incineration process by using a moving grate mechanism to minimize the possibility of formation of NOX. The study found the maximum mass flow rate capacity of incinerator to be 68kg/h with input air A1 as 0.03639 kg/s, input air A2 as 0.03046 kg/s and input air A3 as 0.03409 kg/s. The findings indicated that as capacity is scaled up, the available momentum declines relative to the dimensions of the furnace.

scholarly journals Heat loss from hot water flowing in a copper pipe insulated using air enclosed with a PVC pipe

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
A. Albayani ◽  
M. Mirmanto ◽  
S. Syahrul
Keyword(s):  
Mass Flow Rate ◽  
Heat Loss ◽  
Mass Flow ◽  
Flow Rate ◽  
Test Section ◽  
Hot Water ◽  
Fluid Temperature ◽  
Copper Pipe ◽  
Pvc Pipe ◽  
Bare Copper

This paper presents investigations of heat loss from hot water flowing in an insulated copper pipe. Investigations were performed to know the heat loss from a copper pipe insulated using air enclosed with a PVC pipe. The fluid temperature used was kept at approximately 75°C in the entrance and its mass flow rate was around 12 g/s. The nominal copper pipe diameter was 6.35 mm; while the diameters of the PVC pipe were ranging from 12.7 mm to 5.08 mm. The length of the test section was approximately 3000 mm. The results show that the biggest heat loss is found using the bare copper pipe. When the copper pipe is insulated using air enclosed with a PVC pipe, the heat loss decreases with the increased PVC pipe diameters. The trend of the heat loss agrees with the critical insulation diameter theory.

Dynamic Behavior and Off-Design Performance Analysis of Solar Driven ORC Using Scroll Expanders

2019 ◽  
Author(s):  
Ying Zhang ◽  
Arun Kumar Narasimhan ◽  
Mengjie Bai ◽  
Li Zhao ◽  
Shuai Deng ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
System Level ◽  
Working Fluid ◽  
Small Scale ◽  
Solar Insolation ◽  
Design Performance ◽  
Fluid Mass

Abstract Solar driven ORC system is a possible solution for small-scale power generation. A scroll expander is considered due to its better suitability among other positive displacement expanders for small-scale power outputs. This work conducted a test of an ORC system with an expansion valve by varying the working fluid mass flow rate in two scenarios. A dynamic system-level model of ORC was developed and validated with experimental data. The validated model was used to predict the ORC performance considering off-design conditions of expander and solar insolation. The experimental data showed that pressures and temperatures exhibited the same trend as that of the working fluid mass flow rate, of which the evaporation pressure was the most sensitive to this variation. The simulation results are in good agreement with the experimental results. Results from the dynamic model showed that the ORC power output was underestimated by up to 54.7%, when off-design performance of expander was not considered. Considering the expander off-design performance and solar insolation, a highest thermal efficiency of 7.6% and an expander isentropic efficiency of 80.6% were achieved.

scholarly journals A Model for Igniter Mass Flow Rate History Evaluation for Solid Rocket Motors

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Yanjie Ma ◽  
Futing Bao ◽  
Weihua Hui ◽  
Yang Liu ◽  
Yijie Gao
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Large Scale ◽  
Rocket Motor ◽  
Small Scale ◽  
Solid Rocket Motor ◽  
Combustion Gas ◽  
Proposed Model ◽  
Solid Rocket

This paper describes a zero-dimensional model for evaluating the mass flow rate history of a solid rocket motor igniter. Based on the results of an igniter-firing experiment, in which the igniter is the only source of combustion gas and no propellant is ignited, the proposed model can be used to compute the mass flow rate of the igniter. Different species and temperature-dependent properties, such as the specific heat for each species, are considered. The coupling between the flow field variables in the combustion chamber and the heat transfer at the gas-solid interface is computed in a segment way. Calculations are performed for different species and properties, and the errors are discussed. Using the computed igniter mass flow rate as a boundary condition, a two-dimensional calculation is performed for validation purposes. The results are in good agreement with experimental data. The proposed model can be used to provide reasonable boundary conditions for solid rocket motor simulations and to evaluate the performance of igniters. Although derived on the basis of a small-scale solid rocket motor, the model has the potential to be used in large-scale systems.

scholarly journals Guideline for Electricity Generation from Hot Springs (Natural Energy Storage Systems): A Techno-enviro-economic Assessment

2021 ◽  
Author(s):  
Saeed Ghoddousi ◽  
Behnaz Rezaie ◽  
Samane Ghandehariun
Keyword(s):  
Power Generation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Hot Springs ◽  
Hot Spring ◽  
Water Discharge ◽  
Hot Water ◽  
Specific Investment ◽  
Generation Capacity

The scattered hot springs on the globe are natural thermal energy storages that are available for industrial and recreational advantages. A hot spring is a hydrothermal system that can be used for power generation purposes as well as deep-well geothermal plants. In the present study, a techno-enviro-economic study is conducted to determine the power generation potential of hot springs as a heat source of the Organic Rankine Cycle (ORC). The hot water temperature and discharge mass flow rate from hot springs varies from 60 to 90 ᵒC and 5 to 50 kg/s, respectively. The ORC plant is modeled by Aspen Plus V9. The impacts of the temperature and mass flow rate of discharge from hot springs on the thermodynamics and economics of the plants are investigated. The results indicate that increasing the hot spring temperature and discharge mass flow rate improves the thermal efficiency and power generation capacity of ORC plant while Payback Period (PP), Levelized Energy Cost (LEC), and Specific Investment Cost (SIC) shrink. The power generation capacity varies from 9.3 kW to 303 kW and the LEC range is from 0.03 $/kWh to 0.13 $/kWh based on the hot spring and water discharge mass flow rate.

scholarly journals Heat loss from hot water flowing in a copper pipe insulated using air enclosed with a PVC pipe

2018 ◽  
Vol 8 (1) ◽  
pp. 1
Author(s):  
A. Albayani ◽  
M. Mirmanto ◽  
S. Syahrul
Keyword(s):  
Mass Flow Rate ◽  
Heat Loss ◽  
Mass Flow ◽  
Flow Rate ◽  
Test Section ◽  
Hot Water ◽  
Fluid Temperature ◽  
Copper Pipe ◽  
Pvc Pipe ◽  
Bare Copper

This paper presents investigations of heat loss from hot water flowing in an insulated copper pipe. Investigations were performed to know the heat loss from a copper pipe insulated using air enclosed with a PVC pipe. The fluid temperature used was kept at approximately 75°C in the entrance and its mass flow rate was around 12 g/s. The nominal copper pipe diameter was 6.35 mm; while the diameters of the PVC pipe were ranging from 12.7 mm to 5.08 mm. The length of the test section was approximately 3000 mm. The results show that the biggest heat loss is found using the bare copper pipe. When the copper pipe is insulated using air enclosed with a PVC pipe, the heat loss decreases with the increased PVC pipe diameters. The trend of the heat loss agrees with the critical insulation diameter theory.

scholarly journals Experimental Study of a Concentric Tube Heat Exchanger with Helical Baffle Using CFD

2021 ◽  
Vol 1 (1) ◽  
pp. 32-38
Author(s):  
Jithendra Sai Raja Jithendra Sai RajaChada ◽  
◽  
Akhil Yuvaraj Manda ◽  
Venkat Sandeep Gadi ◽  
Ramasamy Dharmalingam ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Hot Water ◽  
External Diameter ◽  
Tube Heat Exchanger ◽  
Different Temperatures ◽  
Helical Baffle ◽  
Optimum Model

Heat exchangers are the most common equipment used to transfer heat from high-temperature fluid to low-temperature fluid without direct contact. The present study considers the analytical approach on a concentric tube heat exchanger with the helical baffle. The objective of the study is to reduce the size with effect to increase the effectiveness of the heat exchanger. A heat exchanger with 100 mm external diameter and 560 mm length contains a helical baffle with 20 degrees inclination. The designed heat exchanger is analysed by varying the mass flow rate of hot water from 0.25 Kg/s to 2 Kg/s at an interval of 0.25 kg/s at three different temperatures i.e. 363.16 K, 368.16 K, 373.16 K. A nanofluid is applied to cool the hot water without any loss. The mass flow rate of cold fluid is 2 Kg/s at 30 degrees Celsius. The results have displayed that the heat exchanger exhibited appreciable effectiveness at a flow rate of 0.25 Kg/s for hot water at 373.16 K temperature. There by suggesting it as the optimum model of the heat exchanger.

Scaling Effect of Direct Solar Hot Water Systems on Energy Efficiency

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
U. C. Arunachala ◽  
M. Siddhartha Bhatt ◽  
L. K. Sreepathi
Keyword(s):  
Heat Transfer ◽  
Energy Efficiency ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Transfer Rate ◽  
Water Systems ◽  
Hot Water ◽  
Forced Circulation ◽  
Scale Thickness

Scale formation in risers and header of direct solar hot water systems is a problem in places where hard water is being used. In this paper, the effect of scaling on energy efficiency indices such as instantaneous efficiency, mass flow rate, and overall heat loss coefficient are quantified by Hottel–Whillier–Bliss equation in the case of thermosiphon and forced circulation systems. The effect of scaling on mass flow and heat transfer rate for both the systems are quantified with experimental validation. Experimentally found mass flow rate is 50% of the analytical mass flow rate for a clean riser and agrees 99% for the case of riser with 3.75 mm scale thickness. This is due to the extreme change in pressure gain in the narrow region. Scale mapping is done for the entire solar hot water system to study the nature of scale growth. The complete footer and nine risers for the length of 150 mm from footer are free from scaling in axial and radial direction. This is due to the low water temperature in the region. The major portion of header and risers for the length 180 mm from the header are completely blocked due to maximum temperature of water in that region. A scale prediction model is brought out based on the experimentally observed scaled water heaters in the field. It reveals that the major parameters to be considered for the correlation are water total hardness and calcium hardness. It is seen in the thermosiphon system that the mass flow rate decreased by scaling affects energy efficiency more than that caused by the heat transfer rate. The scaling effect is more predominant in thermosiphon systems than in forced circulation systems. The analytical study reveals a drop in instantaneous efficiency of 39.5% in thermosiphon system and 7.0% in the case of forced circulation system for the scale thickness of 3.75 mm. The difference between mass flow rate in scaled and unscaled condition is less in forced circulation but much higher in thermosiphon system.

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