Concentration in evaporators with forced circulation and in-tube boiling of the solution

Abstract Almost 80–90% of energy is wasted as heat (provides no value) in a photovoltaic (PV) panel. An integrated photovoltaic–thermal (PVT) system can utilize this energy and produce electricity simultaneously. In this research, through energy and exergy analysis, a novel design and methodology of a PVT system are studied and validated. Unlike the common methods, here the collector is located outside the PV panel and connected with pipes. Water passes over the top of the panel and then is forced to the collector by a pump. The effects of different water-mass flow rates on the PV panel and collector, individual and overall efficiency, mass loss, exergetic efficiency are examined experimentally. Results show that the overall efficiency of the system is around five times higher than the individual PV-panel efficiency. The forced circulation of water dropped the panel temperature and increased the panel efficiency by 0.8–1% and exergy by 0.6–1%, where the overall energy efficiency was ~81%.

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Optimization of forced circulation to natural circulation transition characteristics of IPWR

Annals of Nuclear Energy ◽

10.1016/j.anucene.2021.108249 ◽

2021 ◽

Vol 157 ◽

pp. 108249

Author(s):

Yifan Xu ◽

Minjun Peng ◽

Genglei Xia ◽

He Shang

Keyword(s):

Natural Circulation ◽

Forced Circulation

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96/00606 Some aspects of a PV/T collector/forced circulation flat plate solar water heater with solar cells

Fuel and Energy Abstracts ◽

10.1016/0140-6701(96)86760-9 ◽

1996 ◽

Vol 37 (1) ◽

pp. 37

Keyword(s):

Solar Cells ◽

Flat Plate ◽

Solar Water Heater ◽

Water Heater ◽

Forced Circulation ◽

Solar Water

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Forced-circulation evaporator with a heating surface area of 800 m2

Chemical and Petroleum Engineering ◽

10.1007/bf01152437 ◽

1975 ◽

Vol 11 (11) ◽

pp. 985-987

Author(s):

V. S. Fokin ◽

E. M. Kovalev ◽

M. K. Kas'yanenko ◽

V. N. Protasenya ◽

V. E. Sereda ◽

...

Keyword(s):

Surface Area ◽

Heating Surface ◽

Forced Circulation ◽

Circulation Evaporator

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Black liquor evaporator upgrades— life cycle cost analysis

TAPPI Journal ◽

10.32964/tj20.3.208 ◽

2021 ◽

Vol 20 (3) ◽

pp. 208-221

Author(s):

JAMES G. CANTRELL

Keyword(s):

Life Cycle ◽

Cost Analysis ◽

North American ◽

Life Cycle Cost ◽

Black Liquor ◽

Unit Mass ◽

Paper Machine ◽

Life Cycle Cost Analysis ◽

Lower Efficiency ◽

Forced Circulation

Black liquor evaporation is generally the most energy intensive unit operation in a pulp and paper manufacturing facility. The black liquor evaporators can represent a third or more of the total mill steam usage, followed by the paper machine and digester. Evaporator steam economy is defined as the unit mass of steam required to evaporate a unit mass of water from black liquor (i.e., lb/lb or kg/kg.) The economy is determined by the number of effects in an evaporator train and the system configuration. Older systems use four to six effects, most of which are the long tube vertical rising film type. Newer systems may be designed with seven or even eight effects using falling film and forced circulation crystallization technology for high product solids. The median age of all North American evaporator systems is 44 years. Roughly 25% of the current North American operating systems are 54 years or older. Older systems require more periodic maintenance and have a higher risk of unplanned downtime. Also, older systems have chronic issues with persistent liquor and vapor leaks, shell wall thinning, corrosion, and plugged tubes. Often these issues worsen to the point of requiring rebuild or replacement. When considering the age, technology, and lower efficiency of older systems, a major rebuild or new system may be warranted. The intent of this paper is to review the current state of black liquor evaporator systems in North America and present a basic method for determining whether a major rebuild or new installation is warranted using total life cycle cost analysis (LCCA).

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Theoretical Considerations of Combined Thermal and Mass Transfer From a Vertical Flat Plate

Journal of Applied Mechanics ◽

10.1115/1.4011304 ◽

1956 ◽

Vol 23 (2) ◽

pp. 295-301

Author(s):

E. V. Somers

Keyword(s):

Mass Transfer ◽

Flat Plate ◽

Fluid Motion ◽

Practical Case ◽

Forced Circulation ◽

Evaporation And Condensation ◽

Mass Transfer Processes ◽

Convective Thermal ◽

Theoretical Considerations ◽

Vertical Flat Plate

Abstract In free-convective processes involving both thermal and mass transfer, since the driving force for the fluid motion has its source solely in the density difference from ambient, it is necessary to consider the thermal and mass-transfer processes simultaneously in solving any given problem. The present problem involves evaporation and condensation phenomena associated with free-convective thermal and mass transfer from a wetted isothermal vertical flat plate to a gas at an ambient temperature and mass concentration different from that on the plate. This problem presents itself in the practical case of vaporization cooling of equipment without forced circulation of the ambient gas.

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Qualitative assessment of air pollution in the working area of energy-intensive materials production by nanoscale aerosols with a solid dispersed phase

Russian Journal of Occupational Health and Industrial Ecology ◽

10.31089/1026-9428-2021-61-12-828-832 ◽

2021 ◽

Vol 61 (12) ◽

pp. 828-832

Author(s):

Boris N. Filatov ◽

Natalya I. Latyshevskaya ◽

Natalya V. Krylova ◽

Irina K. Gorkina ◽

Yulya I. Velikorodnaya ◽

...

Keyword(s):

Air Pollution ◽

Mass Concentration ◽

Solid Phase ◽

Qualitative Assessment ◽

Dust Particles ◽

Dispersed Phase ◽

Forced Circulation ◽

Aluminum Powders ◽

Nanoscale Particles ◽

Wide Range

The presence of grinding, mixing, and fractionation of solid components of formulations leads to the formation of aerosols in the air of the working area with a wide range of dispersion of the solid phase - all this characterizes the organization of technological processes for the production of energy-intensive materials. The study aims to give a qualitative assessment of possible air pollution of the working area of energy-intensive materials production by nanoscale aerosols with a solid dispersed phase. The researchers carried out the sampling of the working area air and flushes from solid horizontal surfaces to produce energy-intensive materials. We carried out the sampling by forced circulation of the test air through the absorption devices of Polezhaev. Scientists used Triton TX-114 solution with a mass concentration of 2.0 mg/dm3 as an absorption medium. The researchers performed flushing from surfaces using cloth tampons moistened with Triton TX-114 solution with a mass concentration of 2.0 mg/dm3. We determined the particle sizes in the samples using NanotracULTRA (Microtrac). Scientists found aluminum and nitrocellulose particles with sizes from 36 to 102 nm in the air of the working area and flushes from horizontal surfaces. The study of the fractional composition of RDX and aluminum powders of the ASD-1 brand showed the presence of nanoscale particles in them. Nanoscale dust particles pollute the air of the working area and solid horizontal surfaces at certain stages of the production of energy-intensive materials. There are nanoscale particles in the composition of powders of some standard components of formulations. Flushes from solid horizontal surfaces are an adequate qualitative indicator of the presence of nanoaerosols in the air of the working area.

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