# IMA**C TEA M 2 A** **PPENDIX J** 

**J2766 Standard for A** **nnualized Climate Calculation of System Power Consumption of a mobile air conditioning**  **ref rigerant**  **system DRAFT** 

SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engi neering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE i nvites your written comments and suggestions. Copyright © 2003 SAE International All rights reserved. No part of this publication may b e reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. **TO PLACE A DOCUMENT ORDER: Tel: 877**  **- 606**  **- 7323 (inside USA and Canada)**  **Tel: 724 -** **776 -** **4970 (outside USA) Fax: 724**  **- 776**  **- 0790**  **Email: custsvc@sae.org SAE WEB ADDRESS:**  **http://www.sae .org**  **1. Scope**  This recommended best practice outlines a method for annualizing the energy consumption of a mobile air conditioning system , given a specified am bient profile range , me asured data on compressor torque as a function of speed and ambient, and a spe cified speed profile.
**2. References**  J2765 Procedure for measuring system COP [Coefficient of Performance] of a mobile air cond i tioning system on a test bench web sites for climate data http://rredc.nrel.gov/solar/pubs/tmy2/tmy2_index.html

. Federal High way Adm inistration, Nationwide Personal Transportation Survey , 1995. http://www
- cta.ornl.gov/npts/1995/Doc/index.shtml US Dept. of Energy , Typical Meteorological Year Data (TMY2) , 1995. [preferred source] http://www.eren.doe.gov/buildings/energy _tools/energyplus/energyplus_weatherdata.html National Renewable Energy Laboratory , TMY2 User’s Manual , 1995. http://rredc.nrel.gov/solar/old_data/nsrdb/tmy2/ Environm ental Systems Research Institute (ESRI), USA Population by County , 1999. http://www.esri.com web s ites for registration data [W ard’s Auto] **3. Capacity and COP data**  Reference data for Capacity and COP shall be collected as described in SAE J2765
- Procedure for me asuring system COP [Coefficient of Performance] of a mobile air cond i tioning system on a test b ench

. The results shall be weighted as outlined in the following paragraphs. **4. Weighting**  **factors for a**  **mbient temperature profile** Decide on the geographic area for which analysis is desired and select specific weather station locations close to the ma

jor me t ropolitan regions in this area. Assign vehicle populations based in these regions to each of these weather stations. T he num ber of weather stations selected should be determined by t he range of climate that exists in the geographic region being studied t he the vehicle population density variation in this region.**SA E J**  **2766 Issued Proposed Draft**  **27jul06**

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- Obtain data by

t im e of day , by

m onth [or by

d ay ] for each weather station from the appropriate reference noted above. Due to shifts in climate data over the recent ye ars, it is recommended that t he climate history b e between 5 and 10 ye ars and as recent as available. Remove the am bient data from 12:00 mi dnight to 6:00AM and create temperature bins in 10 degree C increments showing the frequency t hat each temperature occurs in one year. Add a tabl e to show an example...

We ather station 1 We ather

station 2 We ather

station 3 We ather

station 4 We ighted

average >40 C 30
- 39 C 20
- 29 C 10
- 19 C 1
- 9 C <0 C

**5. Weighting for vehicle registrations**  Obtain vehicle regi strations for each area from the website referenced above. Organize and analy ze the weather data as shown in the table below:

Percent of Vehicle registrations in region We ather station 1 We ather station 2 We ather station 3 We ather station 4 **6. SA** **E J 2766**  **Issued Proposed Draft 27jul06** 

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- **7. We** **ighting for compressor RPM profile**  Collect engine RPM data from the recommended drive shedule shown in the table below for a representative vehicle that is chosen for analysis. Multiple engine RPM data by the compressor to engine drive ratio. Curve fit t he data from SAE J2765 to fit COP vs RPM for each ambient. These curves should have a R2 value of greater than 0.90. [need mo re description here] These curves will then be added to the spreadsheet to predict COP as a function of compressor RPM for each second of the drvie cycle chosen.

**7.1 Elevated idle temperatures at idle**  To compensate for elevated temperatures at the condenser/gas cooler, the COP at speeds less than Idle RPM+50 should use the COP that is measured during SAE J2765 at +15 C temperature a t the inlet.**SA E J**  **2766 Issued Proposed Draft**  **27jul06**

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- **8. Cooling capacity requirement to achieve comfort**  For cooling capacity , it is recommended to use the values shown below. I f the capacity d ata from SAE J2765 supports that the system cannot achieve these values, then the values should be adjus ted according to the data that was measured.

**8.1 Correction for idle capacity capacity vs the stabilized comfort capacity** 

**8.2 Correction for h**  **umidity impact on evaporator capacity**  Organize weather data with associated humidity a nd sort the data by

temperature. Partition the data in 10 degree bins and determine the average hum idity for each temperature bin. C orrect the evaporator capacity for the difference between the tested hum idity i n J2765 and the average hum idity calculated as explained above. D etermine t he enthalpy a t each of the hum idities and correction factor becomes the ratio of the average hum idity to the test hum idity

. [this needs something that addresses the ratio to outlet enthalpy as well...] **8.3 Correction for**  **Solar load impact on evaporator capacity** Organize weather data with associated solar load and sort the data by tem perature. P artition the data in 10 degree bins and determine the average solar load for each temperature bin. C orrect the evaporator capacity for the difference between the tested solar load in J2765 and the average solar load calculated as explained above. D etermine the evaporator load difference by s im ulation or test at different the solar loads and correction factor becomes the ratio of the capacity required for comfort at the average solar load to the test solar load. **9. Correction for elevated temperature in front of condenser or gas cooler** **SA E J**  **2766 Issued Proposed Draft**  **27jul06**

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- **10. Annual Calculation** **SA E J**  **2766 Issued Proposed Draft**  **27jul06**

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- **Rationale** This standard can be used to compare different refrigerant systems. **Relationship of SA E Standard to ISO Standa**  **rd** This standard can be submitted to ISO **Reference Section** SAE J551

—The RefItems style tag is used to list the documents. **Developed By** Team two of the SAE Improved Mobile Air Conditioning Cooperative Research Program **Sponsored By** SAE Interior Clim ate Co ntrol Committee