Semi-transparent Photovoltaic Thermal Greenhouse System Combined with Earth Air Heat Exchanger for Hot Climatic Condition

2021 ◽  
pp. 1-29
Author(s):  
Somil Yadav ◽  
Sarat Kumar Panda ◽  
GN Tiwari ◽  
Ibrahim M. Al-Helal ◽  
Abdullah A Alsadon ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Flow Rate ◽  
Thermal Load ◽  
Climatic Condition ◽  
Optimum Temperature ◽  
Packing Factor ◽  
Solar Radiation Incident ◽  
Periodic Model ◽  
Load Leveling ◽  
Enclosed Space

Abstract Semi-transparent photovoltaic thermal (SPVT) greenhouse system combined with an earth air heat exchanger (EAHE) has been developed to make the system sustainable. The system is designed to cultivate plants in a hot climatic condition, where green net is provided which bifurcates the enclosed space of the greenhouse into zone-1 and zone-2, and this green net cuts the solar radiation incident on the plants. The influence of air changes in zone-1, mass flow rate of air flowing through EAHE, and packing factor on PV cell, air of the greenhouse, and the plant temperatures is investigated for a typical harsh summer day by using periodic model of these parameters. Further, for a holistic performance assessment of this SPVT greenhouse, exergy, thermal load leveling, and decrement factor are evaluated. Results indicate that the optimum temperature range for plant growth (30 °C- 37 °C) within the greenhouse can be achieved through a combination of ventilation in zone-1 and integration of EAHE. The temperature of plants reduced by 9 °C for 30 air changes in zone-1, and the temperature reduces further by 24 °C when EAHE having a flow rate of 0.5 kg/s is operated. The SPVT greenhouse system also generates 128 kWh of daily overall exergy that makes the system sustainable.

Optimal Allocation of Heat Exchanger Inventory for Maximum COP and Exergetic Performance of a Two-Stage Vapor Compression Cycle

2013 ◽  
Author(s):  
Yousef M. Abdel-Rahim ◽  
S. A. Sherif
Keyword(s):  
High Pressure ◽  
Heat Exchanger ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Load ◽  
Low Pressure ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Exergetic Efficiency

In the present study the optimum heat exchanger inventory allocation to maximize the thermal performance of a two-stage vapor compression system with two evaporators has been investigated. Both the cooling (A/C) and heating (H/P) Carnot and non-Carnot non-isentropic cycles have been considered. The optimum operating ranges of cycle parameters that maximize both the coefficient of performance (COP) and exergetic efficiency (η2) of the cycles for both cooling and heating purposes are discussed. The research upon which this paper partly reports covered all possible ranges of cycle parameters using the Monte-Carlo method. For the Carnot cycle, maximum values of the cooling coefficient of performance (COPC), cooling exergetic efficiency (ηIIC), heating coefficient of performance (COPH), and heating exergetic efficiency (ηIIH) were found to be 9.6, 0.47, 10.7 and 0.87, respectively. The low-pressure (LP) thermal load and temperature difference in the condenser were found to critically affect both the A/C and H/P performance, while the heat conductance ratio and the mass flow rate ratio were found to have a pronounced effect on only the H/P performance. The best A/C and H/P cycle performance may be achieved by having the two evaporators with both the thermal load and mass flow rate in the high-pressure loop to be 20% less than that in the low-pressure loop. The analysis performed on the non-Carnot two-compressor, two-evaporator A/C and H/P non-isentropic cycles determined both the feasible and optimal ranges of variations of the controlling parameters. The combined maximum values of the low- and high-pressure evaporator thermal loads was found to be 10–15% lower than the maximum value of the condenser heat rejection rate, thus reflecting the relative sizes of these units as heat exchangers. Other factors that may help provide guidance for utilizing the system for cooling and heating purposes include the values of the COPC and COPH, the relative amounts of the mass flow rates in the low-pressure and high-pressure loops of the cycle, and the values of the low-pressure and high-pressure compressor powers.

scholarly journals Modelling an unconventional closed-loop deep borehole heat exchanger (DBHE): sensitivity analysis on the Newberry volcanic setting

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Hannah R. Doran ◽  
Theo Renaud ◽  
Gioia Falcone ◽  
Lehua Pan ◽  
Patrick G. Verdin
Keyword(s):  
Sensitivity Analysis ◽  
Heat Exchanger ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Energy Flow ◽  
Closed Loop ◽  
Working Fluid ◽  
Valuable Insight ◽  
Deep Borehole

AbstractAlternative (unconventional) deep geothermal designs are needed to provide a secure and efficient geothermal energy supply. An in-depth sensitivity analysis was investigated considering a deep borehole closed-loop heat exchanger (DBHE) to overcome the current limitations of deep EGS. A T2Well/EOS1 model previously calibrated on an experimental DBHE in Hawaii was adapted to the current NWG 55-29 well at the Newberry volcano site in Central Oregon. A sensitivity analysis was carried out, including parameters such as the working fluid mass flow rate, the casing and cement thermal properties, and the wellbore radii dimensions. The results conclude the highest energy flow rate to be 1.5 MW, after an annulus radii increase and an imposed mass flow rate of 5 kg/s. At 3 kg/s, the DBHE yielded an energy flow rate a factor of 3.5 lower than the NWG 55-29 conventional design. Despite this loss, the sensitivity analysis allows an assessment of the key thermodynamics within the wellbore and provides a valuable insight into how heat is lost/gained throughout the system. This analysis was performed under the assumption of subcritical conditions, and could aid the development of unconventional designs within future EGS work like the Newberry Deep Drilling Project (NDDP). Requirements for further software development are briefly discussed, which would facilitate the modelling of unconventional geothermal wells in supercritical systems to support EGS projects that could extend to deeper depths.

Heat and Mass Transfer to Air in a Cross Flow Heat Exchanger with Surface Deluge Cooling

2016 ◽  
Vol 24 (01) ◽  
pp. 1650002 ◽  
Author(s):  
Andrea Diani ◽  
Luisa Rossetto ◽  
Roberto Dall’Olio ◽  
Daniele De Zen ◽  
Filippo Masetto
Keyword(s):  
Heat Exchanger ◽  
Heat Flow ◽  
Flow Rate ◽  
Data Center ◽  
Heat Dissipation ◽  
Cross Flow ◽  
Critical Conditions ◽  
Heat Flow Rate ◽  
External Temperature ◽  
Flow Heat

Cross flow heat exchangers, when applied to cool data center rooms, use external air (process air) to cool the air stream coming from the data center room (primary air). However, an air–air heat exchanger is not enough to cope with extreme high heat loads in critical conditions (high external temperature). Therefore, water can be sprayed in the process air to increase the heat dissipation capability (wet mode). Water evaporates, and the heat flow rate is transferred to the process air as sensible and latent heat. This paper proposes an analytical approach to predict the behavior of a cross flow heat exchanger in wet mode. The theoretical results are then compared to experimental tests carried out on a real machine in wet mode conditions. Comparisons are given in terms of calculated versus experimental heat flow rate and evaporated water mass flow rate, showing a good match between theoretical and experimental values.

Upgrade and Shakedown Test of a High Temperature Fluoride Salt Test Loop

2018 ◽  
Author(s):  
Xiangbo Kong ◽  
Yuan Fu ◽  
Jianyu Zhang ◽  
Huiju Lu ◽  
Naxiu Wang
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchanger ◽  
Flow Rate ◽  
Storage Tank ◽  
Base Alloy ◽  
High Vacuum ◽  
Electric Heater ◽  
Batch Mode ◽  
Test Loop

A FLiNaK high temperature test loop, which was designed to support the Thorium Molten Salt Reactor (TMSR) program, was constructed in 2012 and is the largest engineering-scale fluoride loop in the world. The loop is built of Hastelloy C276 and is capable of operating at the flow rate up to 25m3/h and at the temperature up to 650°C. It consists of an overhung impeller sump-type centrifugal pump, an electric heater, a heat exchanger, a freeze valve and a mechanical one, a storage tank, etc. Salt purification was conducted in batch mode before it was transferred to and then stored in the storage tank. The facility was upgraded in three ways last year, with aims of testing a 30kW electric heater and supporting the heat transfer experiment in heat exchanger. Firstly, an original 100kW electric heater was replaced with a 335kW one to compensate the overlarge heat loss in the radiator. A pressure transmitter was subsequently installed in the inlet pipe of this updated heater. Finally, a new 30kW electric heater was installed between the pump and radiator, the purpose of which was to verify the core’s convective heat transfer behavior of a simulator design of TMSR. Immediately after these above works, shakedown test of the loop was carried out step by step. At first the storage tank was gradually preheated to 500°C so as to melt the frozen salt. Afterwards, in order to make the operation of transferring salt from storage tank to loop achievable, the loop system was also preheated to a relatively higher temperature 530°C. Since the nickel-base alloy can be severely corroded by the FLiNaK salt once the moisture and oxygen concentration is high, vacuum pumping and argon purging of the entire system were alternatively performed throughout the preheating process, with the effect of controlling them to be lower than 100ppm. Once the salt was transferred into the loop, the pump was immediately put into service. At the very beginning of operation process, it was found that flow rate in the main piping could not be precisely measured by the ultrasonic flow meter. Ten days later, the pump’s dry running gas seal was out of order. As a result, the loop had to be closed down to resolve these issues.

scholarly journals Analytical and Experimental Investigation of a Plate Fin Heat Exchanger at Cryogenics Temperature

2021 ◽  
Vol 39 (4) ◽  
pp. 1225-1235
Author(s):  
Ajay K. Gupta ◽  
Manoj Kumar ◽  
Ranjit K. Sahoo ◽  
Sunil K. Sarangi
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Cryogenic Temperature ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Compact Size

Plate-fin heat exchangers provide a broad range of applications in many cryogenic industries for liquefaction and separation of gasses because of their excellent technical advantages such as high effectiveness, compact size, etc. Correlations are available for the design of a plate-fin heat exchanger, but experimental investigations are few at cryogenic temperature. In the present study, a cryogenic heat exchanger test setup has been designed and fabricated to investigate the performance of plate-fin heat exchanger at cryogenic temperature. Major parameters (Colburn factor, Friction factor, etc.) that affect the performance of plate-fin heat exchangers are provided concisely. The effect of mass flow rate and inlet temperature on the effectiveness and pressure drop of the heat exchanger are investigated. It is observed that with an increase in mass flow rate effectiveness and pressure drop increases. The present setup emphasis the systematic procedure to perform the experiment based on cryogenic operating conditions and represent its uncertainties level.

scholarly journals Expanded Microchannel Heat Exchanger: Finite Difference Modeling

Designs ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 58
Author(s):  
David Denkenberger ◽  
Joshua M. Pearce ◽  
Michael Brandemuehl ◽  
Mitchell Alverts ◽  
John Zhai
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Finite Difference ◽  
Flow Rate ◽  
Experimental Results ◽  
Low Flow ◽  
Difference Model ◽  
The Core ◽  
Finite Difference Model ◽  
Flow Maldistribution

A finite difference model of a heat exchanger (HX) considered maldistribution, axial conduction, heat leak, and the edge effect, all of which are needed to model a high effectiveness HX. An HX prototype was developed, and channel height data were obtained using a computerized tomography (CT) scan from previous work along with experimental results. This study used the core geometry data to model results with the finite difference model, and compared the modeled and experimental results to help improve the expanded microchannel HX (EMHX) prototype design. The root mean square (RMS) error was 3.8%. Manifold geometries were not put into the model because the data were not available, so impacts of the manifold were investigated by varying the temperature conditions at the inlet and exit of the core. Previous studies have not considered the influence of heat transfer in the manifold on the HX effectiveness when maldistribution is present. With no flow maldistribution, manifold heat transfer increases overall effectiveness roughly as would be expected by the greater heat transfer area in the manifolds. Manifold heat transfer coupled with flow maldistribution for the prototype, however, causes a decrease in the effectiveness at high flow rate, and an increase in effectiveness at low flow rate.

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.

Thermoregulation of the intra-abdominal testes of the bottlenose dolphin (Tursiops truncatus) during exercise.

1995 ◽  
Vol 198 (1) ◽  
pp. 221-226 ◽  
Author(s):  
D A Pabst ◽  
S A Rommel ◽  
W A McLellan ◽  
T M Williams ◽  
T K Rowles
Keyword(s):  
Heat Exchanger ◽  
Blood Supply ◽  
Thermal Load ◽  
Bottlenose Dolphin ◽  
Linear Array ◽  
Arterial Blood Supply ◽  
Dorsal Fin ◽  
Arterial Blood ◽  
Body Cooling ◽  
Deep Body

Dolphins possess a vascular countercurrent heat exchanger (CCHE) that functions to cool their intra-abdominal testes. Spermatic arteries in the posterior abdomen are juxtaposed to veins returning cooled blood from the surfaces of the dorsal fin and tail flukes. In this study, we investigated the effect of exercise on CCHE function in the bottlenose dolphin. The CCHE flanks a region of the bowel in the posterior abdomen and influences colonic temperatures. A rectal probe housing a linear array of seven copper-constantan thermocouples was designed to measure colonic temperatures simultaneously at positions anterior to, within and posterior to the region of the colon flanked by the CCHE. Immediately after vigorous swimming, temperatures at the CCHE decreased relative to resting and pre-swim values: post-swim temperatures at the CCHE were maximally 0.5 degrees C cooler than pre-swim temperatures. These data suggest that the CCHE has an increased ability to cool the arterial blood supply to the testes when the dolphin is swimming. This ability could offset the increased thermal load on the testes is an exercising dolphin. To the best of our knowledge, this is the first report of deep body cooling in an exercising mammal that is not undertaking a dive.

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