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.

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 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.

Experimental Study on Heat Transfer of Supercritical Kerosene in a Vertical Upward Tube

2013 ◽  
Author(s):  
Dan Huang ◽  
Wei Li ◽  
Wei Zhang ◽  
Guo-Qiang Xu ◽  
Zhi Tao
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Temperature ◽  
Physical Properties ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Supercritical Pressure ◽  
Fluid Temperature ◽  
Thermo Physical Properties

A research on the heat transfer performance of kerosene flowing in a vertical upward tube at supercritical pressure is presented. In the experiments, insights are offered on the effects of the factors such as mass flow rate, heat flux and pressure. It is found that increasing the mass flow rate could enhance the heat transfer performances, while increasing the working pressure will deteriorate the heat transfer. Besides, the effect of heat flux on heat transfer is complicated. Based on the analysis of experimental data, enhancement of heat transfer occurs when the inner wall temperature of tube is higher than pseudo-critical temperature while the bulk fluid temperature is lower than the pseudo-critical temperature. At the supercritical conditions, heat transfer is influenced by the significant changes in thermo-physical properties, thus accurate evaluations of the thermo-physical properties become the key for the supercritical heat transfer calculations. The extended corresponding-state principle could be used for evaluating the density and the transport properties of kerosene, including its viscosity and thermal conductivity, at different temperatures and pressures. In order to obtain the numerical values of the heat capacity, a Soave–Redlich–Kwong (SRK) equation of state is used. The correlation for predicting heat transfer in kerosene at supercritical pressure is established, the calculation results from this correlation are in good agreement with the experimental results.

Analytical and Experimental Investigation to Determine the Variation of Hottel–Whillier–Bliss Constants for a Scaled Forced Circulation Flat-Plate Solar Water Heater

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
U. C. Arunachala ◽  
M. Siddhartha Bhatt ◽  
L. K. Sreepathi
Keyword(s):  
Mass Flow Rate ◽  
Heat Loss ◽  
Mass Flow ◽  
Flow Rate ◽  
Loss Coefficient ◽  
Absorber Plate ◽  
Forced Circulation ◽  
Solar Water ◽  
Scale Thickness ◽  
Overall Heat Loss Coefficient

Fixed tilt flat-plate solar thermal collectors, popularly known as solar water heaters, still remain as one of the most interesting technologies for utilization of solar energy. The system performance deteriorates due to scaling because of the continuous use of hard water as feed water. The present study deals with the experimental and analytical approach to determine the variation of Hottel–Whillier–Bliss (H–W–B) constants (which compactly represent the efficiency characteristics of a solar water heater) due to variation in solar power input and degree of scaling in case of forced circulation system (FCS) without considering the variation of input power to the circulating pump. Indoor tests are performed with a copper tube to investigate the flow characteristics. This forms a part of conventional FCS, in place of the usual nine-fin tube array in a full-fledged collector. In indoor tests, electrical heating is favored to simulate solar radiation level. Various energy parameters are determined and compared by incorporating the developed numerical code FLATSCALE. Variation between experimental and analytical mass flow rate, overall heat loss coefficient, and H–W–B constants with simulated solar radiation level is plotted. In scaled condition, the drop in instantaneous efficiency is due to both scale thickness and reduced water flow rate. Scale thickness acts as an additional thermal conductive resistance between absorber plate and flowing water. Overall heat loss coefficient increases as absorber plate temperature is high during reduced flow rate. The maximum deviation observed is 21.68% in mass flow rate, 14.64% in absorber plate mean temperature, 7.86% in overall heat loss coefficient, and 12.04% in instantaneous efficiency. Compared to a clean tube, a highly scaled tube of 3.7 mm scale thickness indicates a drop of 4.76% in instantaneous efficiency and 40.28% in mass flow rate. It is concluded that the growth of scale in FCS does not affect the instantaneous efficiency significantly because of the margin in heat carrying capacity of water in spite of high drop in the flow rate.

Efficiency and heat loss analysis of honeycomb receiver varying air mass flow rate and beam width

2019 ◽  
Vol 137 ◽  
pp. 1027-1040 ◽  
Author(s):  
Mitsuho Nakakura ◽  
Koji Matsubara ◽  
Selvan Bellan ◽  
Tatsuya Kodama
Keyword(s):  
Mass Flow Rate ◽  
Heat Loss ◽  
Mass Flow ◽  
Flow Rate ◽  
Beam Width ◽  
Air Mass ◽  
Loss Analysis

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.

Resilience Analysis of a Pipe Segment System Carrying Superheated Steam

2014 ◽  
Vol 917 ◽  
pp. 232-243 ◽  
Author(s):  
Sirshendu Guha ◽  
Sudip Kumar Das
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Superheated Steam ◽  
Inlet Pressure ◽  
Inlet Temperature ◽  
Fluid Temperature ◽  
Pipe Length ◽  
Pipe Segment ◽  
Process Fluid

A pipe segment system has been used to estimate its inherent resilience properties for the variation of mass flow rate, inlet temperature and inlet pressure. Superheated steam is taken as the process fluid. The magnitude of the resilience decreases from 927.8 kJ/m3s to 43 kJ/m3s and 31.5 kJ/m3s for variation of mass flow rate, inlet pressure and inlet temperature respectively. In this work, a novel methodology has been described for quantification of inherent system resilience and resilience magnitude has been found to be highest (927.8 kJ/m3s) in case of variation of mass flow rate through the pipe segment system. A useful correlation T = Ta(1-e-nL)+Tse-nL has been formulated for estimation of process fluid temperature, T at any pipe length, L.

Analytical and Experimental Investigation to Determine the Variation of H-W-B Constants for a Scaled Forced Circulation Flat Plate Solar Water Heater

2013 ◽  
Author(s):  
Arunachala Chandavar ◽  
Siddhartha Bhatt ◽  
Sreepathi Krishnamurthy
Keyword(s):  
Mass Flow Rate ◽  
Heat Loss ◽  
Mass Flow ◽  
Flow Rate ◽  
Circulation System ◽  
Absorber Plate ◽  
Forced Circulation ◽  
Solar Water ◽  
Scale Thickness ◽  
Overall Heat Loss Coefficient

Fixed tilt flat plate solar thermal collectors, popularly known as solar water heaters still remain as one of the most interesting technologies for utilization of solar energy. The system performance deteriorates due to scaling because of continuous use of hard water as feed water. The present study deals with the experimental and analytical approach to determine the variation of H-W-B (Hottel–Whillier–Bliss) constants (which compactly represent the efficiency characteristics of a solar water heater) due to variation in solar power input and degree of scaling in case of forced circulation system without considering the variation of input power to the circulating pump. Indoor tests are performed with a copper tube to investigate the flow characteristics. This forms a part of conventional forced circulation system, in place of the usual nine-fin tube array in a full fledged collector. In indoor tests, electrical heating is favored to simulate solar radiation level. Various energy parameters are determined and compared by incorporating the developed numerical code FLATSCALE. Variation between experimental and analytical mass flow rate, overall heat loss coefficient, H-W-B constants with simulated solar radiation level are plotted. In scaled condition, the drop in instantaneous efficiency is due to both scale thickness and reduced water flow rate. Scale thickness acts as an additional thermal conductive resistance between absorber plate and flowing water. Overall heat loss coefficient increases as absorber plate temperature is high during reduced flow rate. The maximum deviation observed is 21.68 % in mass flow rate, 14.64 % in absorber plate mean temperature, 7.86 % in overall heat loss coefficient and 12.04 % in instantaneous efficiency. Compared to a clean tube, a highly scaled tube of 3.7 mm scale thickness indicates a drop of 4.76 % in instantaneous efficiency and 40.28 % in mass flow rate. It is concluded that the growth of scale in forced circulation system does not affect the instantaneous efficiency significantly because of the margin in heat carrying capacity of water inspite of high drop in the flow rate.

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.

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