Lecture 10. Surface Energy Balance (Garratt 5.1-5.2) in This Lecture
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Glossary Physics (I-Introduction)
1 Glossary Physics (I-introduction) - Efficiency: The percent of the work put into a machine that is converted into useful work output; = work done / energy used [-]. = eta In machines: The work output of any machine cannot exceed the work input (<=100%); in an ideal machine, where no energy is transformed into heat: work(input) = work(output), =100%. Energy: The property of a system that enables it to do work. Conservation o. E.: Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. Equilibrium: The state of an object when not acted upon by a net force or net torque; an object in equilibrium may be at rest or moving at uniform velocity - not accelerating. Mechanical E.: The state of an object or system of objects for which any impressed forces cancels to zero and no acceleration occurs. Dynamic E.: Object is moving without experiencing acceleration. Static E.: Object is at rest.F Force: The influence that can cause an object to be accelerated or retarded; is always in the direction of the net force, hence a vector quantity; the four elementary forces are: Electromagnetic F.: Is an attraction or repulsion G, gravit. const.6.672E-11[Nm2/kg2] between electric charges: d, distance [m] 2 2 2 2 F = 1/(40) (q1q2/d ) [(CC/m )(Nm /C )] = [N] m,M, mass [kg] Gravitational F.: Is a mutual attraction between all masses: q, charge [As] [C] 2 2 2 2 F = GmM/d [Nm /kg kg 1/m ] = [N] 0, dielectric constant Strong F.: (nuclear force) Acts within the nuclei of atoms: 8.854E-12 [C2/Nm2] [F/m] 2 2 2 2 2 F = 1/(40) (e /d ) [(CC/m )(Nm /C )] = [N] , 3.14 [-] Weak F.: Manifests itself in special reactions among elementary e, 1.60210 E-19 [As] [C] particles, such as the reaction that occur in radioactive decay. -
Radiant Heating with Infrared
W A T L O W RADIANT HEATING WITH INFRARED A TECHNICAL GUIDE TO UNDERSTANDING AND APPLYING INFRARED HEATERS Bleed Contents Topic Page The Advantages of Radiant Heat . 1 The Theory of Radiant Heat Transfer . 2 Problem Solving . 14 Controlling Radiant Heaters . 25 Tips On Oven Design . 29 Watlow RAYMAX® Heater Specifications . 34 The purpose of this technical guide is to assist customers in their oven design process, not to put Watlow in the position of designing (and guaranteeing) radiant ovens. The final responsibility for an oven design must remain with the equipment builder. This technical guide will provide you with an understanding of infrared radiant heating theory and application principles. It also contains examples and formulas used in determining specifications for a radiant heating application. To further understand electric heating principles, thermal system dynamics, infrared temperature sensing, temperature control and power control, the following information is also available from Watlow: • Watlow Product Catalog • Watlow Application Guide • Watlow Infrared Technical Guide to Understanding and Applying Infrared Temperature Sensors • Infrared Technical Letter #5-Emissivity Table • Radiant Technical Letter #11-Energy Uniformity of a Radiant Panel © Watlow Electric Manufacturing Company, 1997 The Advantages of Radiant Heat Electric radiant heat has many benefits over the alternative heating methods of conduction and convection: • Non-Contact Heating Radiant heaters have the ability to heat a product without physically contacting it. This can be advantageous when the product must be heated while in motion or when physical contact would contaminate or mar the product’s surface finish. • Fast Response Low thermal inertia of an infrared radiation heating system eliminates the need for long pre-heat cycles. -
A Compilation of Data on the Radiant Emissivity of Some Materials at High Temperatures
This is a repository copy of A compilation of data on the radiant emissivity of some materials at high temperatures. White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/133266/ Version: Accepted Version Article: Jones, JM orcid.org/0000-0001-8687-9869, Mason, PE and Williams, A (2019) A compilation of data on the radiant emissivity of some materials at high temperatures. Journal of the Energy Institute, 92 (3). pp. 523-534. ISSN 1743-9671 https://doi.org/10.1016/j.joei.2018.04.006 © 2018 Energy Institute. Published by Elsevier Ltd. This is an author produced version of a paper published in Journal of the Energy Institute. Uploaded in accordance with the publisher's self-archiving policy. This manuscript version is made available under the Creative Commons CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ Reuse This article is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs (CC BY-NC-ND) licence. This licence only allows you to download this work and share it with others as long as you credit the authors, but you can’t change the article in any way or use it commercially. More information and the full terms of the licence here: https://creativecommons.org/licenses/ Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ A COMPILATION OF DATA ON THE RADIANT EMISSIVITY OF SOME MATERIALS AT HIGH TEMPERATURES J.M Jones, P E Mason and A. -
Energy Analysis and Carbon Saving Potential of a Complex Heating
European Journal of Sustainable Development Research 2019, 3(1), em0067 ISSN: 2542-4742 Energy Analysis and Carbon Saving Potential of a Complex Heating System with Solar Assisted Heat Pump and Phase Change Material (PCM) Thermal Storage in Different Climatic Conditions Uroš Stritih 1*, Eva Zavrl 1, Halime Omur Paksoy 2 1 University of Ljubljana, SLOVENIA 2 Çukurova Üniversitesi, TURKEY *Corresponding Author: [email protected] Citation: Stritih, U., Zavrl, E. and Paksoy, H. O. (2019). Energy Analysis and Carbon Saving Potential of a Complex Heating System with Solar Assisted Heat Pump and Phase Change Material (PCM) Thermal Storage in Different Climatic Conditions. European Journal of Sustainable Development Research, 3(1), em0067. https://doi.org/10.20897/ejosdr/3930 Published: February 6, 2019 ABSTRACT Building sector still consumes 40% of total energy consumption. Therefore, an improved heating system with Solar Assisted Heat Pump (SAHP) was introduced in order to minimse the energy consumption of the fossil fuels and to lower the carbon dioxide emissions occurring from combustion. An energy analysis of the complex heating system for heating of buildings, consisting of solar collectors (SC), latent heat storage tank (LHS) and heat pump (HP) was performed. The analysis was made for the heating season within the time from October to March for different climatic conditions. These climatic conditions were defined using test reference years (TRY) for cities: Adana, Ljubljana, Rome and Stockholm. The energy analysis was performed using a mathematical model which allowed hourly dynamics calculation of losses and gains for a given system. In Adana, Rome and Ljubljana, it was found that the system could cover 80% of energy from the sun and the heat pump coefficient of performance (COP) reached 5.7. -
Chapter 8 and 9 – Energy Balances
CBE2124, Levicky Chapter 8 and 9 – Energy Balances Reference States . Recall that enthalpy and internal energy are always defined relative to a reference state (Chapter 7). When solving energy balance problems, it is therefore necessary to define a reference state for each chemical species in the energy balance (the reference state may be predefined if a tabulated set of data is used such as the steam tables). Example . Suppose water vapor at 300 oC and 5 bar is chosen as a reference state at which Hˆ is defined to be zero. Relative to this state, what is the specific enthalpy of liquid water at 75 oC and 1 bar? What is the specific internal energy of liquid water at 75 oC and 1 bar? (Use Table B. 7). Calculating changes in enthalpy and internal energy. Hˆ and Uˆ are state functions , meaning that their values only depend on the state of the system, and not on the path taken to arrive at that state. IMPORTANT : Given a state A (as characterized by a set of variables such as pressure, temperature, composition) and a state B, the change in enthalpy of the system as it passes from A to B can be calculated along any path that leads from A to B, whether or not the path is the one actually followed. Example . 18 g of liquid water freezes to 18 g of ice while the temperature is held constant at 0 oC and the pressure is held constant at 1 atm. The enthalpy change for the process is measured to be ∆ Hˆ = - 6.01 kJ. -
Measurement of the Earth Radiation Budget at the Top of the Atmosphere—A Review
Review Measurement of the Earth Radiation Budget at the Top of the Atmosphere—A Review Steven Dewitte * and Nicolas Clerbaux Observations Division, Royal Meteorological Institute of Belgium, 1180 Brussels, Belgium; [email protected] * Correspondence: [email protected]; Tel.: +32-2-3730624 Received: 25 September 2017; Accepted: 1 November 2017; Published: 7 November 2017 Abstract: The Earth Radiation Budget at the top of the atmosphere quantifies how the Earth gains energy from the Sun and loses energy to space. It is of fundamental importance for climate and climate change. In this paper, the current state-of-the-art of the satellite measurements of the Earth Radiation Budget is reviewed. Combining all available measurements, the most likely value of the Total Solar Irradiance at a solar minimum is 1362 W/m2, the most likely Earth albedo is 29.8%, and the most likely annual mean Outgoing Longwave Radiation is 238 W/m2. We highlight the link between long-term changes of the Outgoing Longwave Radiation, the strengthening of El Nino in the period 1985–1997 and the strengthening of La Nina in the period 2000–2009. Keywords: Earth Radiation Budget; Total Solar irradiance; Satellite remote sensing 1. Introduction The Earth Radiation Budget (ERB) at the top of the atmosphere describes how the Earth gains energy from the sun, and loses energy to space through reflection of solar radiation and the emission of thermal radiation. The ERB is of fundamental importance for climate since: (1) The global climate, as quantified e.g., by the global average temperature, is determined by this energy exchange. -
Light and Illumination
ChapterChapter 3333 -- LightLight andand IlluminationIllumination AAA PowerPointPowerPointPowerPoint PresentationPresentationPresentation bybyby PaulPaulPaul E.E.E. Tippens,Tippens,Tippens, ProfessorProfessorProfessor ofofof PhysicsPhysicsPhysics SouthernSouthernSouthern PolytechnicPolytechnicPolytechnic StateStateState UniversityUniversityUniversity © 2007 Objectives:Objectives: AfterAfter completingcompleting thisthis module,module, youyou shouldshould bebe ableable to:to: •• DefineDefine lightlight,, discussdiscuss itsits properties,properties, andand givegive thethe rangerange ofof wavelengthswavelengths forfor visiblevisible spectrum.spectrum. •• ApplyApply thethe relationshiprelationship betweenbetween frequenciesfrequencies andand wavelengthswavelengths forfor opticaloptical waves.waves. •• DefineDefine andand applyapply thethe conceptsconcepts ofof luminousluminous fluxflux,, luminousluminous intensityintensity,, andand illuminationillumination.. •• SolveSolve problemsproblems similarsimilar toto thosethose presentedpresented inin thisthis module.module. AA BeginningBeginning DefinitionDefinition AllAll objectsobjects areare emittingemitting andand absorbingabsorbing EMEM radiaradia-- tiontion.. ConsiderConsider aa pokerpoker placedplaced inin aa fire.fire. AsAs heatingheating occurs,occurs, thethe 1 emittedemitted EMEM waveswaves havehave 2 higherhigher energyenergy andand 3 eventuallyeventually becomebecome visible.visible. 4 FirstFirst redred .. .. .. thenthen white.white. LightLightLight maymaymay bebebe defineddefineddefined -
A Comprehensive Review of Thermal Energy Storage
sustainability Review A Comprehensive Review of Thermal Energy Storage Ioan Sarbu * ID and Calin Sebarchievici Department of Building Services Engineering, Polytechnic University of Timisoara, Piata Victoriei, No. 2A, 300006 Timisoara, Romania; [email protected] * Correspondence: [email protected]; Tel.: +40-256-403-991; Fax: +40-256-403-987 Received: 7 December 2017; Accepted: 10 January 2018; Published: 14 January 2018 Abstract: Thermal energy storage (TES) is a technology that stocks thermal energy by heating or cooling a storage medium so that the stored energy can be used at a later time for heating and cooling applications and power generation. TES systems are used particularly in buildings and in industrial processes. This paper is focused on TES technologies that provide a way of valorizing solar heat and reducing the energy demand of buildings. The principles of several energy storage methods and calculation of storage capacities are described. Sensible heat storage technologies, including water tank, underground, and packed-bed storage methods, are briefly reviewed. Additionally, latent-heat storage systems associated with phase-change materials for use in solar heating/cooling of buildings, solar water heating, heat-pump systems, and concentrating solar power plants as well as thermo-chemical storage are discussed. Finally, cool thermal energy storage is also briefly reviewed and outstanding information on the performance and costs of TES systems are included. Keywords: storage system; phase-change materials; chemical storage; cold storage; performance 1. Introduction Recent projections predict that the primary energy consumption will rise by 48% in 2040 [1]. On the other hand, the depletion of fossil resources in addition to their negative impact on the environment has accelerated the shift toward sustainable energy sources. -
ALBEDO ENHANCEMENT by STRATOSPHERIC SULFUR INJECTIONS: a CONTRIBUTION to RESOLVE a POLICY DILEMMA? an Editorial Essay
ALBEDO ENHANCEMENT BY STRATOSPHERIC SULFUR INJECTIONS: A CONTRIBUTION TO RESOLVE A POLICY DILEMMA? An Editorial Essay Fossil fuel burning releases about 25 Pg of CO2 per year into the atmosphere, which leads to global warming (Prentice et al., 2001). However, it also emits 55 Tg S as SO2 per year (Stern, 2005), about half of which is converted to sub-micrometer size sulfate particles, the remainder being dry deposited. Recent research has shown that the warming of earth by the increasing concentrations of CO2 and other greenhouse gases is partially countered by some backscattering to space of solar radiation by the sulfate particles, which act as cloud condensation nuclei and thereby influ- ence the micro-physical and optical properties of clouds, affecting regional precip- itation patterns, and increasing cloud albedo (e.g., Rosenfeld, 2000; Ramanathan et al., 2001; Ramaswamy et al., 2001). Anthropogenically enhanced sulfate particle concentrations thus cool the planet, offsetting an uncertain fraction of the anthro- pogenic increase in greenhouse gas warming. However, this fortunate coincidence is “bought” at a substantial price. According to the World Health Organization, the pollution particles affect health and lead to more than 500,000 premature deaths per year worldwide (Nel, 2005). Through acid precipitation and deposition, SO2 and sulfates also cause various kinds of ecological damage. This creates a dilemma for environmental policy makers, because the required emission reductions of SO2, and also anthropogenic organics (except black carbon), as dictated by health and ecological considerations, add to global warming and associated negative conse- quences, such as sea level rise, caused by the greenhouse gases. -
Chapter 2 Solar and Infrared Radiation Fluxes
Chapter 2 Solar and Infrared Radiation Chapter overview: • Fluxes • Energy transfer • Seasonal and daily changes in radiation • Surface radiation budget Fluxes Flux (F): The transfer of a quantity per unit area per unit time (sometimes called flux density). A flux can be thought of as the inflow or outflow of a quantity through the side of a fixed volume. Fluxes can occur in all three directions - Fx, Fy, and Fz What is the convention for the sign of a flux? We can consider fluxes of mass or of heat. What are the units for a mass flux or a heat flux? The amount of a quantity transferred through a given area (A) in a given time (Δt) can be calculated as: Amount = F ⋅ A⋅ Δt For a heat flux, the amount of heat transferred is represented by ΔQH. Note: The textbook discusses kinematic fluxes, but we will not discuss fluxes in these terms in ATOC 3050. Unlike the textbook, we will use the symbol F to represent fluxes, not kinematic fluxes. What processes can cause a heat flux? Radiant flux: The radiant energy per unit area per unit time. Radiant energy: Energy transferred by electromagnetic waves (radiation). Radiation emitted by the sun is referred to as solar or shortwave radiation. Shortwave radiation – refers to the wavelength band (< 4 µm) that carries most of the energy associated with solar radiation Solar constant (or total solar irradiance) (S0): The solar radiative flux, perpendicular to the solar beam, that enters the top of the atmosphere -2 S0 = 1366 W m Radiation emitted by the earth is referred to as longwave, terrestrial, or infrared radiation. -
Psychrometrics Outline
Psychrometrics Outline • What is psychrometrics? • Psychrometrics in daily life and food industry • Psychrometric chart – Dry bulb temperature, wet bulb temperature, absolute humidity, relative humidity, specific volume, enthalpy – Dew point temperature • Mixing two streams of air • Heating of air and using it to dry a product 2 Psychrometrics • Psychrometrics is the study of properties of mixtures of air and water vapor • Water vapor – Superheated steam (unsaturated steam) at low pressure – Superheated steam tables are on page 817 of textbook – Properties of dry air are on page 818 of textbook – Psychrometric charts are on page 819 & 820 of textbook • What are these properties of interest and why do we need to know these properties? 3 Psychrometrics in Daily Life • Sea breeze and land breeze – When and why do we get them? • How do thunderstorms, hurricanes, and tornadoes form? • What are dew, fog, mist, and frost and when do they form? • When and why does the windshield of a car fog up? – How do you de-fog it? Is it better to blow hot air or cold air? Why? • Why do you feel dry in a heated room? – Is the moisture content of hot air lower than that of cold air? • How does a fan provide relief from sweating? • How does an air conditioner provide relief from sweating? • When does a soda can “sweat”? • When and why do we “see” our breath? • Do sailboats perform better at high or low relative humidity? Key factors: Temperature, Pressure, and Moisture Content of Air 4 Do Sailboats Perform Better at low or High RH? • Does dry air or moist air provide more thrust against the sail? • Which is denser – humid air or dry air? – Avogadro’s law: At the same temperature and pressure, the no. -
Assessing Urban Heat Island Mitigation Using Green Roofs: a Hardware Scale Modeling Approach
ASSESSING URBAN HEAT ISLAND MITIGATION USING GREEN ROOFS: A HARDWARE SCALE MODELING APPROACH By William C. Pompeii II A Thesis Submitted to the Department of Geography and Earth Science and the Graduate Council in partial fulfillment of the requirements for the degree of Master of Science in Geoenvironmental Studies SHIPPENSBURG UNIVERSITY Shippensburg, Pennsylvania May, 2010 DEPARTMENT OF GEOGRAPHY AND EARTH SCIENCE SHIPPENSBURG UNIVESITY Upon the recommendation of the chairperson of the department of Geography and Earth Science this thesis is hereby accepted in partial fulfillment of the requirements for the degree of Master of Science in Geoenvironmental Studies Thesis Committee __________________________________________________ ________________ Committee Chairperson Date Dr. Timothy W. Hawkins __________________________________________________ ________________ Committee Member Date Dr. Claire Jantz __________________________________________________ ________________ Committee Member Date Dr. George Pomeroy Table of Contents List of Figures iii List of Tables v ABSTRACT vi Chapter 1: Introduction 1 1.1 Statement of Problem 1 Chapter 2: Review of Literature 3 2.1 Background 3 2.1.1 Urban Heat Island 3 2.2 Green Roofs 6 2.2.1 Origin and Types 6 2.2.2 Benefits of Green Roofs 7 2.3 Chicago-A Case Study City 9 2.3.1 Green Roof Case Study-Chicago City Hall Building 13 2.4 Methods of Study the Urban Heat Island and Benefits of Green Roof Mitigation 15 2.4.1. Urban Heat Island Methods-Dataloggers 15 2.4.2 Green Roof effects on Urban Heat Island