4: Mechanical Cooling
- Page ID
- 18016
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 4.1: Mechanical Cooling – General Applications
- This page discusses mechanical cooling systems used in cars, HVAC units, refrigerators, and building chillers, highlighting the Direct Expansion (DX) cooling cycle's role in transferring heat. It covers hydronic chiller systems for water cooling and the dual functionality of heat pumps, which provide both cooling in summer and heating in winter. This versatility simplifies installations and improves temperature regulation in buildings.
- 4.2: Mechanical Cooling – Principles
- This page discusses mechanical cooling, including refrigeration, air conditioning, and heat pumps. It outlines the principles of thermodynamics that govern these systems, emphasizing that energy is transformed, not created or destroyed. The page explains how heat transfer occurs from warmer to cooler areas, resulting in increased entropy, and describes the function of cooling systems in removing heat and heaters in generating warmth.
- 4.3: Hydronic Cooling Systems
- This page discusses hydronic cooling systems that circulate chilled water through pipes to absorb heat from a room. Warmed water is replaced continuously with chilled water, and an external unit dissipates thermal energy, often located outside. The system can also use underground pipes for better temperature management. Additional cooling methods, such as direct expansion cooling, can be integrated to improve efficiency.
- 4.4: Gas Laws
- This page covers the fundamentals of gas laws for direct expansion cooling systems, defining key concepts such as pressure, temperature, and volume. Pressure is described as force per area, with temperature reflecting thermal energy and measured in Celsius or Kelvin, while volume pertains to the space a substance occupies. It emphasizes the interrelatedness of temperature, pressure, and volume in managing refrigerant behavior in cooling systems.
- 4.5: Phase Changes
- This page discusses the three main forms of matter—solids, liquids, and gases—and their phase changes, particularly regarding cooling systems. It explains that solids have low heat energy compared to liquids and gases. Key concepts include latent heat during phase transitions, where temperature remains constant until completion. Additionally, it covers endothermic and exothermic processes, outlining how cooling systems utilize these properties to manage thermal energy efficiently.
- 4.6: Direct Expansion Air Conditioning Systems
- This page explains the workings of direct expansion (DX) cooling systems, which are used in air conditioners and refrigerators. It highlights the main components: refrigerant, compressor, evaporator, condenser, and expansion valve. The system operates by using thermodynamics to transfer heat, with the compressor driving refrigerant to absorb heat indoors and release it outdoors, while the expansion valve regulates pressure and temperature to ensure effective cooling.
- 4.7: The DX Cooling Cycle
- This page explains the DX cooling cycle, which includes four key components: the compressor, condenser, expansion valve, and evaporator. The compressor raises the temperature of low-pressure gas, which is then cooled and condensed into liquid by the condenser. The expansion valve reduces the pressure and temperature of the refrigerant, creating a cold liquid. The evaporator then absorbs heat from the air, turning the liquid back into gas.
- 4.8: Self Test 4
- This page provides instructions for a self-test that can be taken multiple times, excludes an interactive media element, and offers a link for online access. Quiz questions are also available in the printed versions of the book for offline completion.
Thumbnail: Air conditioners (Unsplash license; Ashkan Forouzani via Unsplash)