LOVELY PROFESSIONAL UNIVERSITY
Academic Task No. 01
School: Mechanical Engineering
Faculty of Thermal Engineering
Name of the faculty member: Dr. Rajesh Choudhary
Course Code: MEC510
Course Title: HVAC Design
Program:
Term: 20212
B.Tech.
Max. Marks: 30
Date of Allotment: February 5, 2021
Is Rubric Applicable: No
Date of Submission: February 11, 2021
Important Guidelines:
1. All questions in this Academic Task are compulsory.
2. It is mandatory to attempt all questions of the assignment in your own handwriting on A4 size
sheets/pages with a blue colour ink pen. Any other mode of attempt (typed or printed codes or table)
except hand written/drawn will not be accepted/considered as valid submission(s) under any
circumstances.
3. Every attempted sheet/page should carry clear details of student such as Name, Registration number,
Roll number, Question number and Page number. The page numbers should be written clearly on the
bottom of every attempted sheet in a prescribed format as: for page 1; Page 1 of 4, for page 2; Page 2 of
4, for page 3; Page 3 of 4 and for page 4; Page 4 of 4, in case your assignment/document is of 4 pages.
4. After attempting the answer(s), student needs to take photograph of each of these answer sheets/pages
and needs to convert the jpeg format images into a sequential single pdf format document (can be done
with many free online available converters).
5. This PDF file should be uploaded onto the UMS interface on or before the last date of the
submission.
6. Refrain from indulging into plagiarism as copy cases will be marked zero.
Evaluation Criterion: Rubrics on different parameters
The assignment is having three sets, which have been allocated as per the table, given below.
Student must submit the allocated assignment only, else, will not be evaluated.
Assignment - 1
Registration
Number
11606042
11606121
11610539
11712475
11800159
11800771
11800974
11800993
11801097
11801598
11801994
11802370
11802797
11803431
11803458
11804200
Assignment Registration Assignment Registration Assignment
Set No.
Number
Set No.
Number
Set No.
A
11804817
B
11901161
C
B
11805841
C
11902190
A
C
11805935
A
11902532
B
A
11806325
B
11903186
C
B
11807119
C
11903975
A
C
11807900
A
11904566
B
A
11808277
B
11905179
C
B
11808424
C
11905376
A
C
11808601
A
11906858
B
A
11810667
B
11909831
C
B
11811043
C
11910462
A
C
11812547
A
11911078
B
A
11813153
B
11912517
C
B
11813845
C
11915334
A
C
11814520
A
11917146
B
A
11815111
B
11917597
C
11917690
A
HVAC Design
Set – A
Date of Allocation: February 5, 2021
Date of Submission: February 11, 2021
Note: It is mandatory to solve all the given questions. Each question is of 10 marks.
1. Explain the purposes of ventilation in any comfort air-conditioning system.
(5 Marks)
2. Explain the decrement factor and time lag and their variations with the thickness of wall.
(5 Marks)
3. Write down the heat balance equation for a human being. Explain various terms and
correlations in details.
(10 Marks)
4. A multi layered wall consists (from inside to outside) 6 mm thick plywood (k=0.6
W/mK), 125 mm thick common brick (k=0.77 W/mK), 2.1 mm thick air space (thermal
conductance=5.8 W/m2K), 125 mm thick common brick and 6 mm thick cement plaster
(k=8.65 W/mK). The values of internal and external surface conductance for the wall are
8.3 and 34.4 W/m2K respectively. Find overall heat transfer coefficient, U of the wall.
What is the value of U, if the air space is replaced by 20 mm thick EPS board (k=0.0377
W/mK)? Assume temperature difference across air space to be 10 K.
(10 Marks)
HVAC Design
Set – B
Date of Allocation: February 5, 2021
Date of Submission: February 11, 2021
Note: It is mandatory to solve all the given questions.
1. Derive the expression for sol-air temperature by considering the correction factor.
(5 Marks)
2. Explain the thermoregulatory process for hotter and colder environment.
(5 Marks)
3. Write down about the choice of inside design conditions for cold storage, industrial airconditioning and comfort air-conditioning, in detail.
(10 Marks)
4. A composite wall is made up of 10 cm of common brick (k = 0.77 W/mK) against 15 cm
of concrete (k = 1.73 W/mK) with 1.25 cm of plaster (k = 8.65 W/m.K) on the inside
wall. Assume still air (surface heat transfer coefficient = 8.5 W/m 2K) in room at 25 °C.
The outside air is at 40 °C. The wind velocity is 25 kmph (surface heat transfer
coefficient = 35 W/m2K). Find: (i) thermal resistance of wall, (ii) overall heat-transfer
coefficient, (iii) steady-state heat transfer per unit area of wall, and (iv) heat transfer if the
outside and inside film resistances are disregarded.
(10 Marks)
HVAC Design
Set – C
Date of Allocation: February 5, 2021
Date of Submission: February 11, 2021
Note: It is mandatory to solve all the given questions.
1. A controlled temperature test room is held at 25 °C. The outside design temperature is 40
°C. The wall is constructed with 2.5 cm pine boards (k = 0.12 W/mK) on the inside and
outside with 10 cm mineral wool block insulation (k = 0.05 W/mK) in between. The pine
boards are placed in position over the insulation by 1.875 cm steel through – bolts placed
at 30 cm centres. Compute the over – all heat – transfer coefficient: (i) Not considering
the presence of bolts, (ii) Considering the presence of bolts. The film coefficient on both
sides of wall is 9.4 W/m2k.
(10 Marks)
2. For an office building in a city having a calculated heating load of 940 kW, estimate the
weight of steam required during the heating season for which the number of degree - days
are 3413. The design outside and inside temperatures are -17 and 21 °C, respectively.
Also estimate the consumption if gas, oil or coal is used instead of steam. The heating
values of the three alternative fuels are 29806 kJ/m3, 4315910 kJ/m3 and 29180 kJ/kg
respectively.
(10 Marks)
3. A hermetically sealed room 4 m x 4 m x 4 m has an internal sensible heat gain of 3 kW.
The overall heat – transfer coefficient of its wall, floor and ceiling is 1.1 W/m 2K. The
outside temperature is constant at 37 °C. Calculate the steady – state temperature of the
room. What will be the temperature maintained inside the room if the ventilation air
supplied is equivalent to 10 air changes per hour?
(5 Marks)
4. Write down about the HEPA and ULPA filters. Also explain the working of any type of
HEPA filter.
(5 Marks)