scholarly journals Heat Flux Based Optimization of Combined Heat and Power Thermoelectric Heat Exchanger

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7791
Author(s):  
Kazuaki Yazawa ◽  
Ali Shakouri
Keyword(s):  
Heat Flux ◽  
Heat Exchanger ◽  
Thermoelectric Materials ◽  
Heat Recovery ◽  
High Efficiency ◽  
Waste Heat ◽  
Combined Heat And Power ◽  
Hot Water ◽  
Maximum Power ◽  
System Efficiency

We analyzed the potential of thermoelectrics for electricity generation in a combined heat and power (CHP) waste heat recovery system. The state-of-the-art organic Rankine cycle CHP system provides hot water and space heating while electricity is also generated with an efficiency of up to 12% at the MW scale. Thermoelectrics, in contrast, will serve smaller and distributed systems. Considering the limited heat flux from the waste heat source, we investigated a counterflow heat exchanger with an integrated thermoelectric module for maximum power, high efficiency, or low cost. Irreversible thermal resistances connected to the thermoelectric legs determine the energy conversion performance. The exit temperatures of fluids through the heat exchanger are important for the system efficiency to match the applications. Based on the analytic model for the thermoelectric integrated subsystem, the design for maximum power output with a given heat flux requires thermoelectric legs 40–70% longer than the case of fixed temperature reservoir boundary conditions. With existing thermoelectric materials, 300–400 W/m2 electrical energy can be generated at a material cost of $3–4 per watt. The prospects of improvements in thermoelectric materials were also studied. While the combined system efficiency is nearly 100%, the balance between the hot and cold flow rates needs to be adjusted for the heat recovery applications.

Analytical and Experimental Study of Potential Heat Recovery From Household Refrigerators

2004 ◽  
Author(s):  
Jessica Todd
Keyword(s):  
Experimental Data ◽  
Heat Exchanger ◽  
Heat Recovery ◽  
Waste Heat ◽  
Tap Water ◽  
Economic Feasibility ◽  
Hot Water ◽  
Coil Design ◽  
Waste Heat Recovery System ◽  
Recovery Potential

Opportunities for waste recovery exist in many types of industrial devices as summarized by Kreith and West [1]. However, no experimental data regarding the potential of heat recovery from household refrigerators have been published in open literature. The decision to implement a heat recovery option depends mostly on convenience and cost. In some cases, however, the decision is difficult because there is a lack of reliable information of the payback for a potential application. This article provides useful information for the design and payback of a waste heat recovery system on a household refrigerator. This paper presents experimental and analytical results of energy recovery potential from the heat rejected by the condenser coils of a household refrigerator. Using a small heat exchanger affixed to the condenser coils, the heat thus recovered can preheat domestic tap water. The analytical study considered three designs: A heat exchanger with the refrigerant condensing on the outside of water pipes, refrigerant on the inside of a counter-flow heat exchanger, and the refrigerant condensing inside a serpentine coil enclosed by a container filled with household tap water. Considering economic feasibility and manufacturing ease, the serpentine coil design was chosen. Experimental data confirmed the heat recovery possibility from the condenser coils. The serpentine coil design can achieve a payback time of 2 to 10 years dependent on whether the domestic hot water uses electric or gas heating.

Electrical and CHP Efficiencies of a 1 MW University Fuel Cell Power Plant

2009 ◽  
Author(s):  
Robert Ryan
Keyword(s):  
Heat Exchanger ◽  
Fuel Cell ◽  
Power Plant ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Hot Water ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Heat Recovery System

A 1 MW fuel cell power plant began operation at California State University, Northridge (CSUN) in January, 2007. The power plant was installed on campus to complement a Satellite Chiller Plant which is being constructed in response to increased cooling demands related to campus growth. The power plant consists of four 250 kW fuel cell units, and a waste heat recovery system which produces hot water for the campus. The waste heat recovery system was designed by CSUN’s Physical Plant Management personnel, in consultation with engineering faculty and students, to accommodate the operating conditions required by the fuel cell units as well as the thermal needs of the campus. A unique plenum system, known as a Barometric Thermal Trap, was created to mix the four fuel cell exhaust streams prior to flowing through a two stage heat exchanger unit. The two stage heat exchanger uses separate coils for recovering sensible and latent heat in the exhaust stream. The sensible heat is being used to partially supply the campus’ building hot water and space heating requirements. The latent heat is intended for use by an adjacent recreational facility at the University Student Union. This paper discusses plant performance data which was collected and analyzed over a several month period during 2008. Electrical efficiencies and Combined Heat and Power (CHP) efficiencies are presented. The data shows that CHP efficiencies have been consistently over 60%, with the potential to exceed 70% when planned improvements to the plant are completed.

scholarly journals Parametric study on heat transfer characteristics of waste heat recovery heat exchanger for automotive exhaust thermoelectric generator

2018 ◽  
Vol 7 (3.3) ◽  
pp. 6
Author(s):  
Ki. Hyun Kim ◽  
Mahesh Suresh Patil ◽  
Jae Hyeong Seo ◽  
Chan Jung Kim ◽  
Gee Soo Lee ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Exchanger ◽  
Numerical Analysis ◽  
Pressure Drop ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Background/Objectives: The parametric study on heat transfer characteristics of waste heat recovery heat exchanger was carried out by varying different geometry parameters to suggest optimum model for automotive exhaust thermoelectric generator.Methods/Statistical analysis: The numerical analysis method was applied to compare the heat transfer characteristics of various heat exchanger models. For numerical analysis, various models were created using computer aided drawing considering different fin arrangements and guide plates. Commercial code ANSYS 17.0 was used to analyze the heat transfer and fluid flow behavior of various models. Mesh independency was conducted to enhance the accuracy of the results.Findings: The thermal performance analysis of waste heat recovery heat exchanger was conducted considering pressure drop and heat flux at cooling side. As the fin spaces were increased, the heat flux at cooling side increased, but pressure drop also increased.Improvements/Applications: The developed geometry can be further optimized considering other geometry parameters and efficient system could be developed for power generation using waste heat with heat recovery exchanger and the present study provides detailed numerical analysis considering pressure drop and heat flux. 

scholarly journals Air purification in industrial plants producing automotive rubber components in terms of energy efficiency

2017 ◽  
Vol 7 (1) ◽  
pp. 106-114 ◽  
Author(s):  
Andrzej Grzebielec ◽  
Artur Rusowicz ◽  
Adam Szelągowski
Keyword(s):  
Energy Efficiency ◽  
Heat Exchanger ◽  
Economic Analysis ◽  
Power Consumption ◽  
Air Temperature ◽  
Heat Recovery ◽  
Waste Heat ◽  
Hot Water ◽  
Air Purification ◽  
Cost Efficient

AbstractIn automotive industry plants, which use injection molding machines for rubber processing, tar contaminates air to such an extent that air fails to enter standard heat recovery systems. Accumulated tar clogs ventilation heat recovery exchangers in just a few days. In the plant in which the research was conducted, tar contamination causes blockage of ventilation ducts. The effect of this phenomenon was that every half year channels had to be replaced with new ones, since the economic analysis has shown that cleaning them is not cost-efficient. Air temperature inside such plants is often, even in winter, higher than 30°C. The air, without any means of heat recovery, is discharged outside the buildings. The analyzed plant uses three types of media for production: hot water, cold water at 14°C (produced in a water chiller), and compressed air, generated in a unit with a rated power consumption of 180 kW. The aim of the study is to determine the energy efficiency improvement of this type of manufacturing plant. The main problem to solve is to provide an air purification process so that air can be used in heat recovery devices. The next problem to solve is to recover heat at such a temperature level that it would be possible to produce cold for technological purposes without air purification. Experimental studies have shown that air purification is feasible. By using one microjet head, a total of 75% of tar particles was removed from the air; by using 4 heads, a purification efficiency of 93% was obtained. This method of air purification causes air temperature to decrease from 35°C to 20°C, which significantly reduces the potential for heat recovery. The next step of the research was designing a cassette-plate heat exchanger to exchange heat without air purification. The economic analysis of such a solution revealed that replacing the heat exchanger with a new one even once a year was not cost-efficient. Another issue examined in the context of energy efficiency was the use of waste heat from the air compressor. Before any changes, the heat was picked up by a chilled water system. The idea was to use the heat for cold generation. Temperature of oil and air in the compressor exceeds 65°C, which makes it a perfect heat source for an adsorption refrigeration device. This solution reduced the cooling demand by 147 kW, thus reducing power consumption by 36.75 kW. This study shows that even in factories where air is heavily polluted with tar, there are huge potentials for energy recovery using existing technical solutions. It is important to note that problems of this kind should always be approached individually.

A Study on Waste Heat Recovery in Drain Water with Water-to-Water Heat Exchanger in Barbershops

2012 ◽  
Vol 608-609 ◽  
pp. 1231-1235
Author(s):  
Fang Tian Sun ◽  
Na Wang ◽  
Xiao Gang Gong ◽  
Yun Ze Fan ◽  
De Ying Li
Keyword(s):  
Heat Exchanger ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Hot Water ◽  
Energy Utilization ◽  
Utilization Efficiency ◽  
Waste Heat Recovery System ◽  
Heat Utilization ◽  
Water Heaters

Heat utilization efficiency of barbershop was about 16.7% in China, because the low-temperature waste water at 30～36°C was directly discharged into sewer. And match of energy grade was not appropriate, because electric water heaters were used to producing hot water at 55～70°C in most of barbershops. A waste heat recovery system with water-to-water heat exchanger (WHR-HE) was presented, according to heat utilization characteristics of barbershop and scientific principle of energy utilization. WHR-HE was analyzed by the first Law of thermodynamics and economics. The analyzed results show that energy consumption can be reduced about 75%, and incremental payback period is less one year for WHR-HE. There is optimal cold side temperature difference of water-to-water heat exchanger.

scholarly journals Studies on the process of recovering low-temperature waste heat from a flue gas in a pilot-scale plant

2016 ◽  
Vol 37 (4) ◽  
pp. 529-543 ◽  
Author(s):  
Piotr Szulc ◽  
Tomasz Tietze ◽  
Kazimierz Wójs
Keyword(s):  
Heat Flux ◽  
Heat Exchanger ◽  
Low Temperature ◽  
Flue Gas ◽  
Waste Heat ◽  
Volumetric Flow Rate ◽  
Pilot Scale ◽  
Hot Water ◽  
Condensing Heat Exchanger ◽  
The Impact

Abstract This paper presents studies carried out in a pilot-scale plant for recovery of waste heat from a flue gas which has been built in a lignite-fired power plant. The purpose of the studies was to check the operation of the heat recovery system in a pilot scale, while the purpose of the plant was recovery of waste heat from the flue gas in the form of hot water with a temperature of approx. 90 °C. The main part of the test rig was a condensing heat exchanger designed and built on the basis of laboratory tests conducted by the authors of this paper. Tests conducted on the pilot-scale plant concerned the thermal and flow parameters of the condensing heat exchanger as well as the impact of the volumetric flow rate of the flue gas and the cooling water on the heat flux recovered. Results show that the system with a condensing heat exchanger for recovery of low-temperature waste heat from the flue gas enables the recovery of much higher heat flux as compared with conventional systems without a condensing heat exchanger.

EXPERIMENTAL INVESTIGATION OF HEAT PIPE HEAT EXCHANGER (HPHE) FOR WASTE HEAT RECOVERY APPLICATION

2019 ◽  
Author(s):  
Sakil Hossen ◽  
AKM M. Morshed ◽  
Amitav Tikadar ◽  
Azzam S. Salman ◽  
Titan C. Paul
Keyword(s):  
Experimental Investigation ◽  
Heat Exchanger ◽  
Heat Pipe ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Pipe Heat

Analysis of Heat Pipe Heat Exchanger (HPHE) For Waste Heat Recovery from an Air Conditioning System

2007 ◽  
Vol 2 (3) ◽  
pp. 86-95
Author(s):  
R. Sudhakaran ◽  
◽  
V. Sella Durai ◽  
T. Kannan ◽  
P.S. Sivasakthievel ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Air Conditioning ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Air Conditioning System ◽  
Pipe Heat

ENERGY EFFICIENT PIPE HEAT EXCHANGER FOR WASTE HEAT RECOVERY FROM EXHAUST FLUE GASES

2017 ◽  
Vol 16 (5) ◽  
pp. 1107-1113 ◽  
Author(s):  
Andrei Burlacu ◽  
Constantin Doru Lazarescu ◽  
Adrian Alexandru Serbanoiu ◽  
Marinela Barbuta ◽  
Vasilica Ciocan ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Energy Efficient ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Flue Gases ◽  
Pipe Heat
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