Performance Evaluations of Extracting Water From Dry Air Using Multi-Stage Desiccant Wheels and Vapor Compression Cycle

2019 ◽  
Author(s):  
Rang Tu ◽  
Lanbin Liu
Keyword(s):  
Water Vapor ◽  
Energy Consumption ◽  
High Temperature ◽  
Low Temperature ◽  
Rural Areas ◽  
Waste Heat ◽  
Dew Point ◽  
Solid Adsorbent ◽  
Multi Stage ◽  
Condense Water

Abstract A water extraction device that takes water from air in dry area is proposed. This device is designed to meet domestic water demand in remote rural areas, where the climate is dry and fresh water is scarce. The device can be driven effectively by low-temperature waste heat and has the characteristics of large daily water production, low energy consumption per unit of water and high water quality. Because the moisture content of air in dry area is very low, the effect of direct condensation is limited. Solid adsorbent is able to adsorb water vapor from air at a low temperature and release water vapor at under high temperature, which can be used for water extracting from air. To improve its performance under dry circumstances, the key technical point of this device is to use solid adsorbent to collect water vapor from other air to raise its dew point temperature, and then use high temperature cold source to condense water vapor from it. In this paper, configurations of the solid adsorption are proposed, which can be driven with low regeneration temperature under the same humidity increasing amount. This device uses multi-stage desiccant wheels to realize humid increasing. Desiccant wheel can be driven with high temperature to take water vapor from dehumidification air and release water vapor to regeneration air. The multi-stage configuration is good for the reduction of regeneration temperature, making applications of low temperature waste heat form heat pumps possible. Then, influencing factors of water extracting rate are analyzed. The influencing of regeneration temperature, humid reduction amount of the humidified air and cooling and heating systems, etc., are analyzed. Last, air handling processes considering cold and heat sources are recommended to reduce energy consumption. The heat pump driven scenarios are discussed in particular. Through optimization, the water extracting rate can be increased and energy consumption per unit of water can be reduced. At present, this paper only studies air water extracting processes and thermal processes, and does not involve structure of the device, water purification and power consumption of fans, etc.

scholarly journals System Design of Electricity Generation Using Waste Heat from LNG Automobile

2020 ◽  
Vol 145 ◽  
pp. 02062
Author(s):  
Canzong Zhou ◽  
Shuyi Chen ◽  
Wei Cui ◽  
Zhengmao Yao
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Electricity Generation ◽  
Waste Heat ◽  
Cooling System ◽  
Combustion Engine ◽  
Lead Telluride ◽  
Maximum Output ◽  
Thermoelectric Conversion ◽  
Temperature Environment

According to the research, thermoelectricity generation can recycle the heat contained in the cooling system of internal combustion engine. This paper is about taking advantage of the feature in the huge temperature difference at about 560 °C which is formed between high-temperature engine and LNG (Liquefied Natural Gas) in low temperature and the ability that LNG provides semiconductor with thermoelectric conversion material so as to produce the maximum output voltage in low temperature. We take advantage of lead telluride materials that adapt to the high temperature environment and bismuth telluride materials that adapt to the low temperature environment, both of which forms a circuit and are designed as a thermoelectric power generation device. Also, we confirm the possibility of applying the device to cars.

Heat and Mass Transfer in Double-Filmwise Heat Exchanger for Industrial Food Processing Applications

2011 ◽  
Author(s):  
Helen Skop ◽  
James Pezzuto ◽  
Valeriy G. Oleynikov-White ◽  
John F. Cavallo ◽  
Robert Fesjian
Keyword(s):  
Water Vapor ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Cost Effective ◽  
Dew Point ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Gas Cooling ◽  
Stack Gas

The baking industry is considered as one of the major energy consuming food industries in North America. More than 40% of bakery fuel consumption is used to evaporate water in the processes [1]. In addition to the baking process’ vapor the oven stack gas contains water vapor from combustion products. Overall the content of water vapor in the typical oven stack gas is about 20% by volume. Most bakeries waste this vapor and its latent heat. Bakeries’ ovens have wide diversity in power and design. Off-the-shelve heat exchangers are not considered as cost effective equipment for stack gas cooling below gas’ dew point temperature. At typical oven stack gas composition water vapor condensation begins to condense at about 72° C. Not using the latent heat of stack water vapor and the heat from gas cooling from dew point temperature to ambient temperature results in low effectiveness of waste heat recovery. Mainly the effect from the recovery of stack gas cooling prior to condensation is considered as non cost effective and waste heat recovery is neglected.

scholarly journals Studi Penambahan Etilena Glikol dalam Menghambat Pembentukan Metana Hidrat pada Proses Pemurnian Gas Alam

2020 ◽  
Vol 14 (2) ◽  
pp. 198
Author(s):  
Muslikhin Hidayat ◽  
Danang Tri Hartanto ◽  
Muhammad Mufti Azis ◽  
Sutijan Sutijan
Keyword(s):  
Water Vapor ◽  
Low Temperature ◽  
Natural Gas ◽  
Operating Temperature ◽  
Hydrate Formation ◽  
Control Unit ◽  
Dew Point ◽  
Heavy Hydrocarbon ◽  
Aspen Hysys ◽  
Point Control

The gas processing facilities are designed to significantly reduce the impurities such as water vapor, heavy hydrocarbon, carbon dioxide, carbonyl sulfide (COS), benzene-toluene-xylene (BTX), mercaptane, and the sulfur compounds. A small amount of those compounds in natural gas is not preferable since they disturb the next processes.  It was proposed to decrease natural gas's operating temperature to -20 ⁰F to remove the impurities from natural gas. The decrease of the natural gas's operating temperature has some consequences to the gas mixers such as hydrate formation at high pressure and low temperature, solidification of ethylene glycol (EG) solution, and the icing of the surface due to low temperature on the surface of chiller (three constraints). The Aspen Hysys 8.8 was used to obtain the suitable flowrate and concentration of the EG solution injected into the natural gas. Peng-Robinson's model was considered the most appropriate thermodynamic property model, and thus it has been applied for this research. The calculation results showed that the EG solution injection would reduce the hydrate formation due to water vapor absorption in the natural gas by EG. The EG solution's flowrate and concentration were varied from 20,000-2,000,000 lb/hr and 80-90 wt.%. When the separation was carried out at the operating temperature of -20 ⁰F, the EG solution's concentration fulfilling the requirement was of 80-84 wt.% with the flowrate of EG solution of 900,000 lb/hr and even more. This amount is not operable. More focused investigation was done for the variation of the operating temperature. Increasing operating temperature significantly reduced the flowrate of EG solution to about 200,000 lb/hr. An alternative process was proposed by focusing on two concentration cases of 80 and 85 % of weight at the low flow rate of EG solution, respectively. These simulations were intended to predict impurities' concentration in the effluent of Dew Point Control Unit (DPCU). The concentrations of BTX, heavy hydrocarbon, mercaptane, and COS flowing out of DPCU were 428.1 ppm, 378.4 ppm, 104 ppm, and 13.3 ppm, respectively. The concentrations of BTX and heavy hydrocarbon are greater than the minimum standard required. It is needed to install an absorber to absorb BTX and heavy hydrocarbon. However, the absorber capacity will be much smaller than if the temperature of natural gas is not decreased and not injected by the EG solution.Keywords: DPCU gas treatment; ethylene glycol solution; hydrate formation; simulationA B S T R A KUnit pengolahan gas dirancang untuk mengurangi sebagian besar senyawa pengotor seperti uap air, hidrokarbon berat, karbon dioksida, karbonil sulfida (COS), benzena-toluena-xilena (BTX), merkaptan, dan senyawa sulfur lainnya. Keberadaan senyawa tersebut dalam gas alam berbahaya karena mengganggu proses selanjutnya walaupun dalam jumlah sedikit. Untuk membersihkan gas alam dari senyawa pengotor, maka suhu operasi gas diturunkan menjadi -20 °F. Penurunan suhu operasi gas dapat menyebabkan pembentukan hidrat pada tekanan tinggi dan suhu rendah, pembekuan larutan etilena glikol (EG), dan pembentukan lapisan es pada permukaan chiller. Aspen Hysys 8.8 digunakan untuk memperkirakan berapa kecepatan alir dan konsentrasi larutan EG yang diinjeksikan ke gas alam. Model Peng-Robinson adalah model termodinamika yang diterapkan untuk penelitian ini. Hasil simulasi menunjukkan bahwa injeksi larutan EG dapat mengurangi pembentukan hidrat karena larutan EG menyerap uap air dalam gas alam. Kecepatan alir dan konsentrasi larutan EG divariasikan dari 20.000-2.000.000 lb/jam dan 80-90 % (%b/b). Saat pemisahan dilakukan pada suhu operasi -20 °F, konsentrasi larutan EG yang memenuhi syarat adalah 80-84 % (%b/b) dengan kecepatan alir larutan EG 900.000 lb/jam atau lebih. Jumlah ini sangat banyak dan kurang layak untuk dioperasikan. Penelitian difokuskan pada variasi suhu operasi. Peningkatan suhu operasi diikuti dengan pengurangan kecepatan aliran larutan EG secara signifikan yaitu menjadi sekitar 200.000 lb/jam. Alternatif proses diusulkan dengan berfokus pada penggunaan kecepatan alir larutan EG yang rendah dengan konsentrasi larutan EG sebesar 80 dan 85 % (%b/b). Simulasi dapat memprediksi konsentrasi pengotor yang keluar dari Dew Point Control Unit (DPCU). Konsentrasi BTX, hidrokarbon berat, merkaptan, dan COS yang mengalir keluar dari DPCU berturut-turut adalah 428,1 ppm, 378,4 ppm, 104 ppm, dan 13,3 ppm. Konsentrasi BTX dan hidrokarbon berat tersebut lebih besar dari standar minimum yang disyaratkan. Oleh karena itu, diperlukan pemasangan absorber untuk menyerap BTX dan hidrokarbon berat. Namun, kapasitas absorber akan jauh lebih kecil apabila dibandingkan dengan kondisi tanpa menurunkan suhu dan menginjeksikan oleh larutan EG.Kata kunci: DPCU; larutan etilena glikol; pembentukan hidrat; simulasi 

scholarly journals Analysis and Evaluation of Multi-Energy Cascade Utilization System for Ultra-Supercritical Units

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3969
Author(s):  
Shidan Chi ◽  
Tao Luan ◽  
Yan Liang ◽  
Xundong Hu ◽  
Yan Gao
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Waste Heat ◽  
Heat Rate ◽  
Large Temperature ◽  
Feed Water ◽  
Coal Consumption ◽  
Mass Transfer Processes ◽  
Exhaust Heat ◽  
New System

To address the large temperature difference in the air heater (AH) inlet of a traditional exhaust heat utilization system and energy grade mismatch problems during the heat and mass transfer processes, this study proposed a new multi-level waste heat cascade utilization system. Based on a principle of “temperature-to-port and cascade utilization”, this system uses the boiler side high-temperature flue gas and low-temperature air, and the turbine side high-temperature feed water and low-temperature condensate water, to conduct cross heat exchange according to the energy grade matching principle. Combined with a typical 1000 MW coal-fired unit, the heat transfer characteristics and energy-saving benefits of the new system were analyzed. The results showed that the new system has excellent performance: the heat rate decreased by 91 kJ/kWh, coal consumption decreased by 3.3 g/kWh, and power generation efficiency increased to 49.39%.

scholarly journals Experimental investigation of the ecological hybrid refrigeration cycle

2014 ◽  
Vol 35 (3) ◽  
pp. 145-154
Author(s):  
Piotr Cyklis ◽  
Ryszard Kantor ◽  
Tomasz Ryncarz ◽  
Bogusław Górski ◽  
Roman Duda
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Heat Source ◽  
Waste Heat ◽  
Temperature Limit ◽  
Working Fluid ◽  
Temperature Cycle ◽  
Compression System ◽  
High Temperature Limit ◽  
University Of Technology

Abstract The requirements for environmentally friendly refrigerants promote application of CO2 and water as working fluids. However there are two problems related to that, namely high temperature limit for CO2 in condenser due to the low critical temperature, and low temperature limit for water being the result of high triple point temperature. This can be avoided by application of the hybrid adsorption-compression system, where water is the working fluid in the adsorption high temperature cycle used to cool down the CO2 compression cycle condenser. The adsorption process is powered with a low temperature renewable heat source as solar collectors or other waste heat source. The refrigeration system integrating adsorption and compression system has been designed and constructed in the Laboratory of Thermodynamics and Thermal Machine Measurements of Cracow University of Technology. The heat source for adsorption system consists of 16 tube tulbular collectors. The CO2 compression low temperature cycle is based on two parallel compressors with frequency inverter. Energy efficiency and TEWI of this hybrid system is quite promising in comparison with the compression only systems.

Performance Evaluation of Multi-Stage Shell and Tube Transport Membrane Condenser Heat Exchangers for Low Grade Waste Heat and Water Recovery

2017 ◽  
Author(s):  
Soheil Soleimanikutanaei ◽  
Cheng-Xian Lin ◽  
Dexin Wang
Keyword(s):  
Water Vapor ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Power Plants ◽  
Ceramic Membrane ◽  
Waste Heat ◽  
Low Grade ◽  
Water Recovery ◽  
Multi Stage ◽  
Shell And Tube

In this work for the first time the performance of multi-stage shell and tube Transport Membrane Condenser (TMC) based heat exchangers are evaluated numerically. The present heat exchanger is design to work under high pressure and temperature condition for both heat and water recovery in Oxy-Combustion processes. TMC heat exchangers use the nano-porous and ceramic membrane technology to extract the water vapor and latent heat of condensation from the flue-gas. The most important application of TMC heat exchangers is in the power plants which the water vapor in the presence of other non-condensable gases (i.e. CO2, O2 and N2) exist. Effect of the different arrangement of the multi-stage shell and tube TMC heat exchangers, number of branches and number of heat exchangers in each branch on the heat transfer and water recovery have been studied numerically. A single phase multi-component model is used to assess the capability of single stage TMC heat exchangers in terms of waste heat and water recovery at various inlet conditions. Numerical simulation has been performed using ANSYS-FLUENT software and the condensation rate model has been implemented applying User Define Function. Finally, an optimum configuration for the TMC heat exchanger unit has been proposed and the results of numerical simulations are depicted in terms of temperature and water vapor mass fraction contours.

scholarly journals Experimental Study of Condensation in a Thermoacoustic Cooler With Various 3D-Printed Regenerators Using Water Vapor as the Working Fluid

2019 ◽  
Vol 142 (5) ◽  
Author(s):  
Aibek Bekkulov ◽  
Andrew Luthen ◽  
Ben Xu
Keyword(s):  
Water Vapor ◽  
Low Temperature ◽  
Temperature Gradient ◽  
Sound Wave ◽  
Cooling Capacity ◽  
Working Fluid ◽  
Cooling Power ◽  
Parallel Plates ◽  
Humid Air ◽  
Condense Water

Abstract Thermoacoustics (TA) deals with the conversion of heat into sound and vice versa. The device that transfers energy from a low-temperature reservoir to a high-temperature one by utilizing acoustic work is called TA cooler (TAC). The main components of a typical TAC are a resonator, a porous regenerator (e.g., stack of parallel plates), and two heat exchangers. The thermoacoustic phenomenon takes place in the regenerator where a nonzero temperature gradient is imposed and interacts with the sound wave. The low temperature at the cold end of TAC can be used to condense water from the humid air and also reduce the moisture. In the current study, the sound wave with high intensity was produced to drive a TAC to produce cooling power at a cold temperature around 18 °C, using saturated water vapor as the working fluid. The drainage of condensate in the regenerator is the key to the system’s performance. This work is dedicated to investigate the effect from temperature gradient created in TAC on the condensation enhancement, by adopting three different designs of regenerators. A 3D printer was used to design and fabricate different structures of regenerator, and then, the systematic cooling capacity was tested and compared with different regenerators. This work can be extended to evaluate how the TA effect can be affected by the condensation if humid air is directly used as the working fluid. The potential application of this investigation can be an autonomous TAC system for water harvesting in arid areas.

scholarly journals EXPERIMENTAL ANALYSIS OF A HEAT PUMP ASSISTED RECUPERATIVE AIR DEHUMIDIFIER

2004 ◽  
Vol 3 (1) ◽  
Author(s):  
C. A. B. Pereira ◽  
R. H. Pereira ◽  
R. P. Marques ◽  
J. A. R. Parise ◽  
J.R. Sodré
Keyword(s):  
Water Vapor ◽  
Energy Consumption ◽  
Heat Pump ◽  
Experimental Analysis ◽  
Open Circuit ◽  
Dew Point ◽  
Air Stream ◽  
Controlling Parameter ◽  
Experimental Apparatus ◽  
Low Humidity

This paper describes the experimental analysis of a heat pump assisted recuperative air dehumidifier. The system consisted of an air-to-air vapor compression heat pump, coupled to the air ducting. Dehumidification was generated by reduction of the air temperature through the evaporator below the dew point, and thus promoting the condensation of the water vapor. Moist air was then warmed up in the condenser, resulting in a lowtemperature low-humidity air stream. Low energy consumption values are achieved in such systems as the latent heat of the water vapor acts as the heat pump own heat source. Occasionally, the compressor heat is also recoverable. The innovative feature of the present analysis was the introduction of an air-to-air plate recuperator, to further promote dehumidification, yet at the expense of greater compressor energy consumption. An experimental apparatus was constructed to perform comparative tests of the dehumidifier operating with and without the recuperator. A closed air circuit was employed, with the air mass flow rate as the controlling parameter of the experiment. Tests were also carried out with an open circuit.

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