Optimization of a Thermoelectric Cooler for Time-Varying Heat Load and Sink Temperature

2013 ◽  
Author(s):  
Matthew R. Pearson ◽  
Charles E. Lents
Keyword(s):  
Heat Load ◽  
Thermal Conductance ◽  
Electronics Cooling ◽  
Operating Conditions ◽  
Time Varying ◽  
Worst Case ◽  
Operating Cycle ◽  
Temperature Function ◽  
Thermoelectric Coolers ◽  
A Tec

Thermoelectric coolers (TECs) are solid-state cooling devices that operate on the Seebeck effect. They can be used in electronics cooling applications as well as other refrigeration systems. Among the various factors that affect TEC performance within a system, it has been shown that the thermal conductance is an important parameter which can also be easily altered during the design of a TEC to deliver optimal TEC performance for a given application. However, these studies have considered only a fixed heat load and heat sink temperature, whereas in many realistic applications these quantities can vary. A procedure has been developed for optimizing the thermal conductance of a TEC based on a typical operating cycle of time-varying heat load and sink temperature, while permitting constraints that ensure that one or more worst-case operating conditions can also be met. This procedure is valid for any arbitrary heat load and sink temperature functions; however, for illustrative purposes, a simple heat load function at fixed sink temperature (and a sink temperature function at fixed heat load) are used. The results show that the optimal conductance can strongly depend on the operating cycle, and the corresponding reduction in electrical input work (and corresponding increase in net COP) can be significant.

Optimization of a Thermoelectric Cooler for Time-Varying Heat Load and Sink Temperature

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Matthew R. Pearson ◽  
Charles E. Lents
Keyword(s):  
Heat Load ◽  
Thermal Conductance ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Time Varying ◽  
Worst Case ◽  
Operating Cycle ◽  
Temperature Function ◽  
Thermoelectric Coolers ◽  
A Tec

Thermoelectric coolers (TECs) are solid-state cooling devices that operate on the Seebeck effect. They can be used in electronic cooling applications as well as other refrigeration systems. Among the various factors that affect TEC performance within a system, it has been shown that the thermal conductance is an important parameter, which can also be easily altered during the design of a TEC to deliver optimal TEC performance for a given application. However, these studies have considered only a fixed heat load and heat sink temperature, whereas in many realistic applications these quantities can vary. A procedure has been developed for optimizing the thermal conductance of a TEC based on a typical operating cycle of time-varying heat load and sink temperature, while permitting constraints that ensure that one or more worst-case operating conditions can also be met. This procedure is valid for any arbitrary heat load and sink temperature functions; however, for illustrative purposes, a simple heat load function at fixed sink temperature (and a sink temperature function at fixed heat load) is used. The results show that the optimal conductance can strongly depend on the operating cycle, and the corresponding reduction in electrical input work (and corresponding increase in net coefficient of performance (COP)) can be significant.

scholarly journals Selection of Heat Pump Capacity Used at Thermal Power Plants under Electricity Market Operating Conditions

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 226
Author(s):  
Milana Treshcheva ◽  
Irina Anikina ◽  
Vitaly Sergeev ◽  
Sergey Skulkin ◽  
Dmitry Treshchev
Keyword(s):  
Electric Power ◽  
Heat Pump ◽  
Heat Load ◽  
Power Plants ◽  
Thermal Power ◽  
Heat Pumps ◽  
Operating Conditions ◽  
Energy Resources ◽  
Thermal Power Plants ◽  
Maximum Heat

The percentage of heat pumps used in thermal power plants (TPPs) in the fuel and energy balance is extremely low in in most countries. One of the reasons for this is the lack of a systematic approach to selecting and justifying the circuit solutions and equipment capacity. This article aims to develop a new method of calculating the maximum capacity of heat pumps. The method proposed in the article has elements of marginal analysis. It takes into account the limitation of heat pump capacity by break-even operation at electric power market (compensation of fuel expenses, connected with electric power production). In this case, the heat pump’s maximum allowable capacity depends on the electric capacity of TPP, electricity consumption for own needs, specific consumption of conditional fuel for electricity production, a ratio of prices for energy resources, and a conversion factor of heat pump. For TPP based on combined cycle gas turbine (CCGT) CCGT-450 with prices at the Russian energy resources markets at the level of 2019, when operating with the maximum heat load, the allowable heat pump capacity will be about 50 MW, and when operating with the minimum heat load—about 200 MW.

Efficient Analysis of a Catenary Riser

2006 ◽  
Author(s):  
Elizabeth Passano ◽  
Carl M. Larsen
Keyword(s):  
Operating Conditions ◽  
Stochastic Simulations ◽  
Worst Case ◽  
Nonlinear Structure ◽  
Tension Response ◽  
Extreme Response ◽  
Analysis Strategies ◽  
Low Tension ◽  
Term Response

The paper deals with the challenge of predicting the extreme response of catenary risers, a topic of both industry and academic interest. Large heave motions introduced at the upper end of a catenary riser can lead to compression and large bending moments in the region immediately above the touch down area. In the worst case, dynamic beam buckling may occur. The focus of the paper will be on understanding the riser behaviour in extreme, low-tension response and in establishing suitable analysis strategies to predict the extreme response. Results from long nonlinear stochastic simulations of many sea states with varying environmental and operating conditions may be combined to describe the long-term response of a nonlinear structure such as a catenary riser. However, this theoretically straight-forward approach is very demanding computationally and ways to limit the extent of nonlinear stochastic simulations are therefore sought. The usefulness of simpler methods such as regular wave analysis to improve understanding of the physical behaviour and to aid in concentrating the nonlinear simulations to where they are most useful, will be demonstrated.

Numerical Optimization of the Thermoelectric Cooling Devices

2005 ◽  
Author(s):  
B. Abramzon
Keyword(s):  
Electric Current ◽  
Optimum Design ◽  
Random Search ◽  
Thermal Conductance ◽  
Physical Parameters ◽  
Thermoelectric Cooling ◽  
Thermoelectric Coolers ◽  
Independent Variables ◽  
Cooling Devices ◽  
Optimization Search

The present study proposes the unified numerical approach to the problem of optimum design of the thermoelectric devices for cooling electronic components. The method is illustrated with several examples which are based on the standard mathematical model of a single-stage thermoelectric cooler with constant material properties. The model takes into account the thermal resistances from the hot and cold sides of the TEC. Values of the main physical parameters governing the TEC performance (Zeebeck coefficient, electrical resistance and thermal conductance) are derived from the manufacturer catalog data on the maximum achievable temperature difference, and the corresponding electric current and voltage. The independent variables for the optimization search are the number of the thermoelectric coolers, the electric current and the cold side temperature of the TEC. The additional independent variables in other cases are the number of thermoelectric couples and the height-to area ratio of the thermoelectric pellet. The objective for the optimization search is the maximum of the total cooling rate or maximum of COP. In the present study, the problems of optimum design of thermoelectric cooling devices are solved using the so-called Multistart Adaptive Random Search (MARS) method [16].

Using Sliding Mode Control to Adjust Drum Level of a Boiler Unit With Time Varying Parameters

2010 ◽  
Author(s):  
Hamed Moradi ◽  
Firooz Bakhtiari-Nejad ◽  
Majid Saffar-Avval ◽  
Aria Alasty
Keyword(s):  
Water Level ◽  
Transfer Functions ◽  
Sliding Mode ◽  
Operating Conditions ◽  
Model Parameters ◽  
Feed Water ◽  
Time Varying ◽  
Boiler Unit ◽  
Varying Parameters ◽  
Time Varying Parameters

Stable control of water level of drum is of great importance for economic operation of power plant steam generator systems. In this paper, a linear model of the boiler unit with time varying parameters is used for simulation. Two transfer functions between drum water level (output variable) and feed-water and steam mass rates (input variables) are considered. Variation of model parameters may be arisen from disturbances affecting water level of drum, model uncertainties and parameter mismatch due to the variant operating conditions. To achieve a perfect tracking of the desired drum water level, two sliding mode controllers are designed separately. Results show that the designed controllers result in bounded values of control signals, satisfying the actuators constraints.

Introduction of the Taurus™ 65 Industrial Gas Turbine for Power Generation

2008 ◽  
Author(s):  
George Rocha ◽  
Simon Reynolds ◽  
Theresa Brown
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Electrical Power ◽  
Field Evaluation ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Liquid Fuels ◽  
Operating Cycle ◽  
Product Experience ◽  
Exhaust Heat

Solar Turbines Incorporated has combined proven technology and product experience to develop the new Taurus 65 gas turbine for industrial power generation applications. The single-shaft engine is designed to produce 6.3 megawatts of electrical power with a 33% thermal efficiency at ISO operating conditions. Selection of the final engine operating cycle was based on extensive aerodynamic-cycle studies to achieve optimum output performance with increased exhaust heat capacity for combined heat and power installations. The basic engine configuration features an enhanced version of the robust Centaur®50 air compressor coupled to a newly designed three-stage turbine similar to the Taurus 70 turbine design. Advanced cooling technology and materials are used in the dry, lean-premix annular combustor, consistent with Solar’s proven SoLoNOx™ combustion technology, capable of reducing pollutant emissions while operating on standard natural gas or diesel liquid fuels. Like the Titan™ 130 and Taurus 70 products, a traditional design philosophy has been applied in development of the Taurus 65 gas turbine by utilizing existing components, common technology and product experience to minimize risk, lower cost and maximize durability. A comprehensive factory test plan and extended field evaluation program was used to validate the design integrity and demonstrate product durability prior to full market introduction.

Computer simulation of the reliability of the heat exchange surface of the steam turbine condenser

2022 ◽  
pp. 1748006X2110672
Author(s):  
Krzysztof Bernard Łukaszewski
Keyword(s):  
Heat Exchange ◽  
Steam Turbine ◽  
Cooling Water ◽  
Operating Conditions ◽  
Time Varying ◽  
Turbine Condenser ◽  
Heat Exchange Surface ◽  
Steam Turbine Condenser ◽  
The Relationship ◽  
Exchange Surface

The aim of the article is to demonstrate the relationship between the adaptive regulation of the heat exchange surface to specific operating conditions of a steam turbine condenser and the reliability and availability of this surface in a specific period of time. The article exemplifies the relationship between the settings of the condenser heat exchange surface and the resulting changes in the reliability structures of this surface. The method of creating a mathematical model of reliability estimation, which is characterized by the variability of the reliability structures of the heat exchange surface in relation to specific operating conditions in a specific period of time, was indicated. Then, exemplary simulations of the adaptation of reliability structures of specific pipe systems constituting the condenser’s heat exchange surface to specific processes of operation of this condenser are presented. The simulations refer to the time-varying thermal loads of the condenser, the time-varying mean thickness of the sediments, and changes in the temperature of the cooling water at the point of its intake over time. The adaptation of certain reliability structures consists in the adaptation of specific systems of pipes through which the cooling water flows to the currently existing operating conditions of the condenser in order to maintain the desired reliability of the heat exchange surface for a specified time. This is done by enabling or disabling the flow of cooling water through a given number of pipes in specific systems under given operating conditions. On the basis of computer simulations, the reliability functions, and the availability functions of the subsystem under consideration were estimated.

Capillary Pumped Loop Heat Spreader for Electronics Cooling

2001 ◽  
Author(s):  
Jaewon Chung ◽  
Costas P. Grigoropoulos ◽  
Ralph Greif
Keyword(s):  
Electronics Cooling ◽  
Cooling Capacity ◽  
Impinging Jets ◽  
Heat Sinks ◽  
Manufacturing Cost ◽  
Air Cooling ◽  
Capillary Pumped Loop ◽  
Heat Spreader ◽  
Vertical Orientation ◽  
Thermoelectric Coolers

Abstract As cooling requirements for electronic devices, e.g. computer processor units, power modules, etc. increase beyond the capabilities of air-cooling, interest has moved to several alternatives such as thermoelectric coolers, impinging jets and heat exchangers with phase change. Included among these, the capillary pumped loop is a very competitive cooling device, because of its performance reliability, no power requirements and low manufacturing cost. In this paper, a heat spreader employing capillary pumped loop principles was made of aluminum and copper and tested. The copper CPL heat spreader with heat sinks and fans on the condenser (86mm thick, 60mm wide, 181mm long) has demonstrated a cooling capacity of 640W at atmospheric pressure in the vertical orientation and maintains a difference between TIHE (temperature of the interface between heater and evaporator) and TAMB (ambient temperature) lower than 100°C.

Does the Burning of Moxa (Artemisia vulgaris) in traditional Chinese medicine constitute a health hazard?

2009 ◽  
Vol 27 (1) ◽  
pp. 16-20 ◽  
Author(s):  
John Wheeler ◽  
Belinda Coppock ◽  
Cecil Chen
Keyword(s):  
Carbon Monoxide ◽  
Chinese Medicine ◽  
Traditional Chinese Medicine ◽  
Health Hazard ◽  
Urban Environments ◽  
Operating Conditions ◽  
Therapeutic Modality ◽  
Worst Case ◽  
Safety Standards ◽  
Exposure Levels

Background Concerns have been expressed about potential toxicity of the smoke produced by the burning of moxa in traditional Chinese medicine. With the advent of strict anti-smoking legislation in the UK, it was decided to test the volatiles produced by moxibustion and compare them with current agreed safe exposure levels. Method Moxa, in the form of cigar shaped moxa “sticks” or “rolls”, was tested under International Organization for Standardization conditions in a tobacco testing laboratory, and the quantities of a number of pre-determined volatiles measured. The smoke tested was “sidestream smoke”, the smoke which arises from the burning tip of the moxa. The test results were then scaled up to reflect normal use and to provide direct comparisons with agreed national safety standards for both short- and long-term exposure levels. Results Levels of only two volatiles produced were equivalent or greater than the safe exposure levels, as was the carbon monoxide level reported, both as a consequence of using worst case assumptions for comparison. Under normal operating conditions neither volatile nor carbon monoxide would present a safety hazard. One group of chemicals tested, the aromatic amines, with known carcinogenic properties have no agreed safety levels. Results for these in the study compared favourably with background levels reported in urban environments. Conclusion There are no immediate concerns arising from the continued use of moxa as a therapeutic modality in traditional Chinese medicine. Further testing may be required to establish whether current recommendations for ventilation and cleansing of treatment room surfaces may need to be revised. Stronger recommendations may also be necessary on the inadvisability of using moxa on broken skin.

A Novel Methodology for Optimal Design of Compressor Plants Using Probabilistic Plant Design

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Rainer Kurz ◽  
J. Michael Thorp ◽  
Erik G. Zentmyer ◽  
Klaus Brun
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Operating Conditions ◽  
Process Conditions ◽  
Plant Design ◽  
Well Performance ◽  
Worst Case ◽  
Gas Industry ◽  
Machine Performance ◽  
Equipment Sizing

Equipment sizing decisions in the oil and gas industry often have to be made based on incomplete data. Often, the exact process conditions are based on numerous assumptions about well performance, market conditions, environmental conditions, and others. Since the ultimate goal is to meet production commitments, the traditional method of addressing this is to use worst case conditions and often adding margins onto these. This will invariably lead to plants that are oversized, in some instances, by large margins. In reality, the operating conditions are very rarely the assumed worst case conditions, however, they are usually more benign most of the time. Plants designed based on worst case conditions, once in operation, will, therefore, usually not operate under optimum conditions, have reduced flexibility, and therefore cause both higher capital and operating expenses. The authors outline a new probabilistic methodology that provides a framework for more intelligent process-machine designs. A standardized framework using a Monte Carlo simulation and risk analysis is presented that more accurately defines process uncertainty and its impact on machine performance. Case studies are presented that highlight the methodology as applied to critical turbomachinery.

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