This document proposes using solar and ram air energy for bus air conditioning. It describes the current fuel-based refrigeration system and then presents ideas to replace it. The proposed system would use a fan to draw in ram air through the bus roof. This air would pass through a heat exchanger and expansion valve to cool the bus interior without using fuel. Diagrams show the system's components, including the solar panels, fan, heat exchanger, expansion valve, and air ducts. Formulas are provided for calculating air properties and system performance. Specifications of the roof design and components are also listed.

1. PRESENTED BY:
NAME.
VISHWENDRA
SUDHANSHU SHEKHAR
VAIBHAV NEGI

2. INTRODUCTION
• FUEL CRISES IS THE BIGGEST PROBLEM OF
MODERN ERA
• USE OF FUEL IS MAINLY IN TRANSPORTATION
• FUEL CONSUMPTION IS MORE IN AC BUSES
• TO REDUCE THIS RENEWABLE SOURCE OF ENERGY
HAS TO BE USED
• THE USE OF SOLAR ENERGY AND AIR AS A FUEL
SHOULD BE IMPLEMENTED FOR REFRIGERATION

3. PRESENT SYSTEM

4. PROCESS
CONDENSOR
FILTER
AND
SIGHT GLASS
EXPANSION
VALVE
EVAPORATOR
COMPRESSORTHERMOSTAT
ELECTRICAL WIRE
GAS
REFRIGERRATION
GAS TO LIQUID
LIQUID
INSPECTED
PRESSURE AND
TEMP DOWN
LIQUID TO GAS
HT &HP
∆ HEAT
REJECTION
HEAT FROM
PESSANGER
COMPARTMENT

5. IDEAS
IMPLEMENTED

6. IDEA
• USE OF OPEN AIR CYCLE: CYCLE IN WHICH
ATMOSPHERIC AIR IS TAKEN IN FOR PROCESSING.
• USE OF RAM AIR SYSTEM THAT IS USED IN AIRCRAFT.
• USE OF RENEWABLE ENERGY SOURCE: SOLAR
ENERGY USED FOR RUNNING THE COMPONENTS OF
COOLING SYSTEM.
• ECO FFREINDLY: NO USE OF FUEL AT ANY STAGE.

7. RAM AIR CONCEPT
• IT IS THE AIRFLOW CREATED BY MOVING OBJECT.
• CHARACTERSTICS OF RAM AIR ARE
1.Low Velocity
2.Low temperature and
3.Static pressure is high.
• IT’S MAIN APPLICATION IS FOUND IN AIRCRAFT
COOLING SYSTEM.

8. MODIFICATION
• HEIGHT REDUCED
• BACK SEATS ELIMINATED
• ROOF MODIFIED

9. ROOF

10. COMPONENTS
• SOLAR ENERGY
SYSTEM
• FAN
• HEAT EXCHANGER
• EXPANSION VALVE
• NOZZLE
• EXHAUST FAN
• PIPING SYSTEM
• BATTERY
• THERMOSTAT

11. COMPONENTS SPECIFICATION
• FAN : Increases velocity, pressure ratio is 1.01
• ROOF DIMENSIONS : Height equals to 25,20 cm
Length equals to 5,3m respectively.
• EXPANSION VALVE : Works under Joule Thomson effect
• HEAT EXCHANGER : Cross flow type heat exchanger
• SOLAR PANEL SYSTEM : Used to generate power upto 3.6 KW
• NOZZLE : For supply of air to the cabin
• THERMOSTAT : Measurement of temperature
• AIR FILTER : For dust free air
• PIPING SYSTEM : For flow of air among several components

12. SYSTEM

13. FORMULA USED
T1=T+[v^2/2000*Cp] [for calculation of ram air temperature]
Where,
T1=Ram air temperature.
T=Ambient air temperature.
v=Velocity of vehicle
Cp=Specific heat capacity of air at constant pressure
A=l*b [for getting area]
Where,
A=Area
l=length
b=breadth

14. Q =A*v [Q= discharge volume of air]
P= (m*R*T1)/V [for getting pressure of air inside]
Where,
m=Mass flow rate of air[ m=Q* ρ(Density of air)]
R= Charecterstic gas constant
P= Pressure of air inside
P2/P=T2 /T1 =p[for getting pressure of air coming out of fan by pressure
ratio(p)]
Where,
P2=Pressure of air coming out of fan
T2=Temperature of air coming out of fan
p= Pressure ratio

15. T3=T1-( μ)*(dp)[for getting temperature coming out of expansion valve]
Where,
T3=Temperature coming out of expansion valve
μ =Joule-Thomson expansion constant
dp=Pressure difference
μ =[v*( α *T1-1)]/Cp
Where,
α=Thermal expansion coefficient of air
ε ={T2-T4/T2-T3} [for getting temperature coming out of heat exchanger]
Where,
ε = Effectiveness of heat exchanger
T4= Air coming out of heat exchanger with temperature drop

16. CONSIDERED DATA
A.) T=40 deg cel [degree celcius]
B.) v=50 m/sec [metre/second]
C.) ρ =1.275 kg/m cube
D.) Annual speed of air= 7.4 miles/hour [1miles/hour=.447 m/sec]
E.) Ambient pressure=1 bar
F.) 1k[Kelvin]=1 deg cel+273
G.) p=1.01
H.) R=.287 kJ/kg k [kilo joule/ kilogram Kelvin]
Where,
R=R(bar)/M
*For air R(bar) [Universal gas constant]=8.314 kJ/kg mol k & M
(Molecular mass)= 28.96 kg

17. I.) Cp= 1.005 kj/kg k
J.) Cv= .717 kj/kg k
K.) α = 3.2*10^(-3) celcius inverse
L.) ε=0.5
M.) Assuming our solar cell to be 20% efficient so it will
produce 2 watt power in 0.001 m sq area (m sq= metre
square)
N.) Dimensions of roof top staircase:
L (Length): 8m
H (Height):25cm
B (Breadth):2m.
O.) Battery: 24 volt DC supply
P.) Fan: 1m diameter with DC supply 5,10,25 volts [as
per requirement ]

20. AIR DUCT

21. Inner View of Compressor

22. Space for Cooling Agent

23. Heat Exchanger

24. Expansion Valve

25. Cooled Cabin