{"id":2500,"date":"2023-06-19T08:56:12","date_gmt":"2023-06-19T08:56:12","guid":{"rendered":"https:\/\/fairconditioning.org\/fc-activity\/?post_type=activity&p=2500"},"modified":"2023-06-19T08:56:12","modified_gmt":"2023-06-19T08:56:12","slug":"energy-saving-from-higher-temperature-setting","status":"publish","type":"activity","link":"https:\/\/fairconditioning.org\/fc-activity\/activity\/energy-saving-from-higher-temperature-setting\/","title":{"rendered":"Energy Saving from Higher Temperature Setting"},"content":{"rendered":"\n
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Objective<\/h5>\n\n\n\n

To estimate the energy savings from an AC by maintaining the thermostat at a higher temperature.<\/p>\n\n\n\n

Outcome<\/h5>\n\n\n\n

Students will realise that considerable energy savings can be achieved just through setting higher temperature in cooled spaces.\u00a0\u00a0<\/p>\n\n\n\n

Requirements<\/h5>\n\n\n\n

Psychrometric chart<\/p>\n\n\n\n

Prerequisites<\/h5>\n\n\n\n

Conceptual knowledge of psychrometry.<\/p>\n\n\n\n

Given Data:<\/em><\/strong><\/p>\n\n\n\n

Design Conditions (peak summer)<\/p>\n\n\n\n

    \n
  1. Ambient condition : DB = 40\u00b0C, RH = 60%<\/li>\n\n\n\n
  2. Desired condition for scenario 1 : DB = 22\u00b0C, RH = 50%<\/li>\n\n\n\n
  3. Desired condition for scenario 2 : DB = 25\u00b0C, RH = 50%<\/li>\n\n\n\n
  4. Density of air : 1.12 kg\/m3<\/sup><\/li>\n\n\n\n
  5. 4 air changes per hour<\/li>\n\n\n\n
  6. 120 sq. ft. room, 10 ft. ceiling height<\/li>\n<\/ol>\n\n\n\n

    Conversion Factors:<\/p>\n\n\n\n

      \n
    1. 1 kW = 1 kJ\/s<\/li>\n\n\n\n
    2. 1 hr = 3,600 s<\/li>\n\n\n\n
    3. 1 m3<\/sup> = 35.32 ft3<\/sup><\/li>\n\n\n\n
    4. 1 TR = 3.517 kW of cooling<\/li>\n<\/ol>\n\n\n\n
      Procedure<\/h5>\n\n\n\n

      Step 1: <\/em><\/strong>On the psychrometric chart, estimate Enthalpy (H) of ambient air condition and desired conditions for both scenarios (kJ\/kg) and find the differences (\u2206H1<\/sub> & \u2206H2<\/sub>).<\/p>\n\n\n\n

      Step 2: <\/em><\/strong>Estimate required volumetric air flow rate (m3<\/sup>\/hr).<\/p>\n\n\n\n

      Step 3:<\/em><\/strong> Convert volumetric air flow rate (m3<\/sup>\/hr) to mass flow rate (kg\/hr).<\/p>\n\n\n\n

      Step 4: <\/em><\/strong>Estimate cooling required for scenario 1 (kJ\/s).<\/p>\n\n\n\n

      Step 5:<\/em><\/strong> Estimate cooling required for scenario 2 (kJ\/s).<\/p>\n\n\n\n

      Step 6:<\/em><\/strong> Estimate the percentage energy savings.<\/p>\n\n\n\n

      Calculations:<\/em><\/strong><\/p>\n\n\n\n

      Step 1:<\/em><\/strong> Enthalpy of<\/p>\n\n\n\n

        \n
      1. Ambient condition (Ha<\/sub>) = 114kJkg<\/li>\n\n\n\n
      2. Desired condition 1 (Hd1<\/sub>) = 42kJkg<\/li>\n\n\n\n
      3. Desired condition 2 (Hd2<\/sub>) = 50kJkg<\/li>\n<\/ol>\n\n\n\n

        \u0394H1<\/sub> = Ha<\/sub> – Hd1<\/sub> = <\/em>114-42 = 72kJkg <\/p>\n\n\n\n

        \u0394H2<\/sub> = Ha<\/sub> – Hd2<\/sub> = 114-50 = 64kJkg<\/p>\n\n\n\n

        Step 2: <\/em><\/strong>volumetric air flow rate (va<\/sub>) (m3hr) = air changes per hour (1hr) volume of the room (ft3)35.32 (ft3m3)
        = 4 120 1035.32  
        = 135.84m3hr <\/p>\n\n\n\n

        Step 3:<\/em><\/strong> mass flow rate (ma<\/sub>) (kghr) = va<\/sub> (m3hr) x density of air (kgm3)<\/p>\n\n\n\n

        = 135.8 x 1.12<\/p>\n\n\n\n

        = 152.1kghr<\/p>\n\n\n\n

        Step 4: <\/em><\/strong>Cooling required for case 1 (L1<\/sub>) (kJs) =m<\/sub>a<\/sub> (kghr) \u0394H1(kJkg)3600 (shr) <\/p>\n\n\n\n

        =152.14 723600 <\/p>\n\n\n\n

        = 3.043kJs<\/p>\n\n\n\n

        Step 5: <\/em><\/strong>Cooling required for case 2 (L2<\/sub>) (kJs) =m<\/sub>a<\/sub> (kghr) \u0394H2(kJkg)3600 (shr) <\/p>\n\n\n\n

        =152.14 643600 <\/p>\n\n\n\n

        = 2.705kJs<\/p>\n\n\n\n

        Step 6:<\/em><\/strong> Percentage energy savings = L1 – L2L1x 100<\/p>\n\n\n\n

        = 3.043 – 2.7053.043<\/p>\n\n\n\n

        =  11.1% <\/strong><\/p>\n\n\n\n

        Image:<\/em><\/strong><\/p>\n\n\n\n

        \"\"\/<\/figure>\n\n\n\n
        References<\/h5>\n\n\n\n

        None<\/p>\n\n\n\n

        Source of Idea<\/h5>\n\n\n\n

        <\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

        Objective To estimate the energy savings from an AC by maintaining the thermostat at a higher temperature. Outcome Students will realise that considerable energy savings can be achieved just through setting higher temperature in cooled spaces.\u00a0\u00a0 Requirements Psychrometric chart Prerequisites Conceptual knowledge of psychrometry. Given Data: Design Conditions (peak summer) Conversion Factors: Procedure Step 1: […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","template":"","meta":{"inline_featured_image":false},"activity_subject":[124,125],"academic_year":[68,69],"complexity":[],"content_tags":[387,416,431,514],"activity_type":[371],"activity_duration":[515],"acf":[],"_links":{"self":[{"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/activity\/2500"}],"collection":[{"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/activity"}],"about":[{"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/types\/activity"}],"author":[{"embeddable":true,"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/comments?post=2500"}],"version-history":[{"count":1,"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/activity\/2500\/revisions"}],"predecessor-version":[{"id":2501,"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/activity\/2500\/revisions\/2501"}],"wp:attachment":[{"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/media?parent=2500"}],"wp:term":[{"taxonomy":"activity_subject","embeddable":true,"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/activity_subject?post=2500"},{"taxonomy":"academic_year","embeddable":true,"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/academic_year?post=2500"},{"taxonomy":"complexity","embeddable":true,"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/complexity?post=2500"},{"taxonomy":"content_tags","embeddable":true,"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/content_tags?post=2500"},{"taxonomy":"activity_type","embeddable":true,"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/activity_type?post=2500"},{"taxonomy":"activity_duration","embeddable":true,"href":"https:\/\/fairconditioning.org\/fc-activity\/wp-json\/wp\/v2\/activity_duration?post=2500"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}