Algal biomass harvesting using low-grade waste heat: the effect of waste heat temperature and air speed on dewatering algal suspension

Biofuels ◽  
2021 ◽  
pp. 1-11
Author(s):  
Ramin E. Yazdi ◽  
Temesgen Garoma
Keyword(s):  
Algal Biomass ◽  
Waste Heat ◽  
Low Grade ◽  
Heat Temperature ◽  
Biomass Harvesting ◽  
Algal Suspension ◽  
Air Speed

scholarly journals Performance analysis on series and parallel circuit configurations of a four-cell thermoelectric generator module design

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Muhammad Hadrami Hamdan ◽  
◽  
Nur Aqilah Mat Som ◽  
Amirul Abdul Rashid ◽  
Gilbert Jugi Jimmy ◽  
...  
Keyword(s):  
Forced Convection ◽  
Thermoelectric Generator ◽  
Waste Heat ◽  
Proton Exchange ◽  
Heating Element ◽  
Low Grade ◽  
Good Prospect ◽  
Heat Temperature ◽  
Module Design ◽  
Parallel Circuit

This study presents a technique in recovering energy from low-grade waste heat of a Proton Exchange Membrane Fuel Cell (PEMFC). The goal is to study the functionality and performance using a multiple cell thermoelectric generator (TEG) module. The test bench consists of a heating element, a test section, and a cooling section. The heating element supplies a hot stream temperature of 53°C and 58°C that represents the waste heat from an actual PEMFC stack. The module comprises four TEG cells with heat pipes coupled with a heat sink system. The main variables were the TEG cooling modes of natural convection (0 m/s) and forced convection (at 5 m/s and 10 m/s) and the series and parallel circuit configurations of the module. At 58°C waste heat temperature, forced convection cooling at 10 m/s gave the highest voltage and power output of 140 mV and 1960 µW. The outputs of the series circuit was 159% higher than the parallel circuit. This initial simple TEG module design has shown that it has a good prospect to compensate for the ultra-low waste heat temperature of a PEMFC. Future designs of the modules need to identify a more optimized approach to improve the outputs and contribute to the long-term sustainability of PEMFC systems.

Algal biomass harvesting using low-grade waste heat: Investigation of dewatering algal suspension by evaporation

2021 ◽  
pp. 1-12
Author(s):  
Ramin E. Yazdi ◽  
Temesgen Garoma
Keyword(s):  
Heat Exchanger ◽  
Algal Biomass ◽  
Evaporation Rate ◽  
Waste Heat ◽  
Methyl Esters ◽  
Operating Conditions ◽  
Water Evaporation ◽  
Low Grade ◽  
Gas Temperature ◽  
Algae Biomass

Abstract This study investigated the feasibility of harvesting algae biomass using an original and novel method that uses low-grade waste heat with an integrated heat exchanger, evaporation tank, and reservoir system. Several experiments were conducted. The experimental results showed good agreement with theoretical results estimated with a stagnant-film model. As the inlet gas temperature increased from 175 to 245°C, the evaporation rate increased by 100%, while an 85% increase was achieved as the air speed increased from 0 to 3.5 m/s. It was also observed that the evaporation rate slightly decreased when doubling the volume of the reservoir while it is independent of the duration of experiment. The amount of lipid extracted from centrifuged algae was slightly higher than algae harvested by evaporation. However, the total amount of fatty acid methyl esters (FAMEs) was significantly higher, by 24%, for the algae harvested by evaporation compared to centrifugation. The FAMEs profiles were the same for both methods and about 98% of FAMEs were C-16 and C-18 carbon chains which are the main components of the algal biodiesel. The method has a potential to be developed into a cost-effective and energy efficient algal biomass dewatering method. It uses low-grade waste heat, which is cheap and readily available, and has simple and inexpensive structures. It was also demonstrated that modifying the proposed system, by adding a second heat exchanger in series, improved the water evaporation rate by 58 to 121%, depending on the operating conditions.

Sludge Disposal from an Island Community

1992 ◽  
Vol 25 (12) ◽  
pp. 33-47 ◽  
Author(s):  
T. S. C. Gross ◽  
R. R. Cohen
Keyword(s):  
Agricultural Land ◽  
Waste Heat ◽  
Treatment Plant ◽  
Small Island ◽  
Low Grade ◽  
Sludge Disposal ◽  
Disposal Option ◽  
Total Process ◽  
Island Community ◽  
Farm Produce

The small island of Jersey is served by a single wastewater treatment plant at Bellozanne. Since its inception some 30 years ago the sludge produced has been used on agricultural land. Inevitably there are circumstances which prevent this happening without interruption, eg, poor weather, or seasonal demand. On these occasions, the island has no other disposal option to fall back on. Furthermore, concerns over the practice have created a perception that it might be doing harm to the ‘quality' of the farm produce. The responsible body, the Public Services Department, formulated a flexible, multiple option solution and commissioned Halcrow to engineer the capital works. The works centre around a thermal drying plant using biogas produced by the digestion process as the main fuel. Waste heat is recovered for digester heating making the total process potentially self sufficient in energy. At the same time, the bulk of the product is reduced considerably, providing an easily transported material with potential for use directly on the land as a fertilizer substitute or as a low grade fuel. Farfrom being a disposal problem requiring manpower and expense, sludge will soon be regarded by the States of Jersey as a valuable resource with a revenue potential.

scholarly journals Efficient and affordable thermomagnetic materials for harvesting low grade waste heat

APL Materials ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 011105
Author(s):  
Daniel Dzekan ◽  
Anja Waske ◽  
Kornelius Nielsch ◽  
Sebastian Fähler
Keyword(s):  
Waste Heat ◽  
Low Grade

A Parametric Examination of the Factors Affecting the Performance of a Diffusion Absorption Refrigeration System

2021 ◽  
pp. 1-38
Author(s):  
Noman Yousuf ◽  
Timothy Anderson ◽  
Roy Nates
Keyword(s):  
Waste Heat ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Low Grade ◽  
Absorption Refrigeration ◽  
Factors Affecting ◽  
Thermally Driven ◽  
Mass Flowrate ◽  
Diffusion Absorption

Abstract Despite being identified nearly a century ago, the diffusion absorption refrigeration (DAR) cycle has received relatively little attention. One of the strongest attractions of the DAR cycle lies in the fact that it is thermally driven and does not require high value work. This makes it a prime candidate for harnessing low grade heat from solar collectors, or the waste heat from stationary generators, to produce cooling. However, to realize the benefits of the DAR cycle, there is a need to develop an improved understanding of how design parameters influence its performance. In this vein, this work developed a new parametric model that can be used to examine the performance of the DAR cycle for a range of operating conditions. The results showed that the cycle's performance was particularly sensitive to several factors: the rate of heat added and the temperature of the generator, the effectiveness of the gas and solution heat exchangers, the mass flowrate of the refrigerant and the type of the working fluid. It was shown that can deliver good performance at low generator temperatures if the refrigerant mass fraction in the strong solution is made as high as possible. Moreover, it was shown that a H2O-LiBr working pair could be useful for achieving cooling at low generator temperatures.

Design and Analysis of a High Power Density, Low Temperature Waste Heat Recovery System Using an Oil-Free Turboalternator

2010 ◽  
Author(s):  
James F. Walton ◽  
Andrew Hunsberger ◽  
Hooshang Heshmat
Keyword(s):  
Output Power ◽  
Waste Heat ◽  
Maximum Output Power ◽  
Output Power Level ◽  
Working Fluid ◽  
Prototype System ◽  
Low Grade ◽  
Maximum Output ◽  
Test Results ◽  
Study Results

In this paper the authors will present the design and preliminary test results for a distributed electric generating system that uses renewable energy source for economical load-following and peak-shaving capability in an oil-free, high-speed micro-turboalternator system using compliant foil bearings and a permanent magnet alternator. Test results achieved with the prototype system operating to full speed and under power generating mode will be presented. A comparison between predicted and measured electrical output will also be presented up to a power generating level of 25 kWe at approximately 55,000 rpm. The excellent correlation between design and test provides the basis for scale up to larger power levels. Based upon the turboalternator test results a thermodynamic cycle analysis of a system using low grade waste heat water at approximately 100 C will be reviewed. The tradeoff study results for a series of environmentally friendly refrigerant working fluids will also be presented including sensitivity to vaporization and condensing temperatures. Based on the cycle and pinch point analyses predicted maximum output power was determined. Finally a preliminary turbine design for the selected R134a working fluid was completed. The results of this study show that a net output power level of greater than 40 kW is possible for approximately 240 l/m flow of water at 100C is possible.

Sign in / Sign up

Export Citation Format

Share Document