Saving energy by solar collector and heat pump combination in hot water

production in residential and hotel sectors

Dr. Nguyen Nguyen An, HUST

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Energy consumption to produce hot water inresidential and hotel sectors

Current solutions to save energy in hot waterproduction

Solar collector and heat pump combination in hotwater production (SHCS – Solar & Heat pumpCombination System)

Some achievements of SHCS project Conclusions

CONTENTS

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Energy consumption to produce hotwater in Vietnam

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Lighting27%

Hot water18%

Air conditioning

45%

Others10%

Residential Energy Consuption in Vietnam

Lighting

Hot water

Air conditioning

Others

Lighting20%

Hot water30%

Air conditioning

50%

Hotel Energy Consumption in Vietnam

Lighting

Hot water

Air conditioning

Energy consumption to produce hotwater in other country

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Energy consumption to produce hotwater

Current solutions to save energy in hotwater production

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Using solar collector: “zero” energy consumptionbut strongly influenced by weather condition.

Using hot water heat pump (HWHP): low energyconsumption (about 1/3 of resistant element waterheater) but required regularly maintenance.

Using both solar collector and HWHP: workingnon-influenced by weather, almost “zero” energyconsumption, requirement of regularlymaintenance will be reduced but required highinitial cost.

Solar collector and Heat pumpCombination System - SHCS

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Main ideas of SHCS project:◦ Reduce the heating capacity (so reduce the initial cost) of

the HWHP by increasing the volume of the hot waterstorage tank.◦ Develop an intelligent controller that can automatically

operate the HWHP based on the amount of hot waterrequired by the load in “future”. Currently, the HWHPcontroller works based on the “set temperature” only.◦ Develop a design tool (dynamic simulation basic) which

can determine the heating capacity of the HWHP fromweather data analysis and the pattern of hot water load.

Solar collector and Heat pumpCombination System - SHCS

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Goals of SHCS project:◦ Design, install and test a prototype of SHCS to produce

hot water for a 5-person house in Vietnam.◦ Design, install and test a prototype of SHCS to produce

hot water for a 220-room, 4-star hotel in Vietnam.◦ Develop a controller algorithm for SHCS.◦ Develop a Computer Aided Design (CAD) software for

SHCS.

Some achievements of SHCS project

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water for a 5-person house in Vietnam

Diagram of SHCS

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water for a 5-person house in Vietnam

System specifications:- Location: Hanoi capital- Total volume of hot water storage: 250 liters- Solar collector type: vacuum tube, D58 mm- Number of vacuum tube: 20- Absorption area of solar collector: 2.64 m2

- Heating capacity of HWHP: 950 W (20.4% of usual requirement of 4.65 kW)

- Heating COP: 3.25- Daily hot water usage: 150 liters

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water for a 5-person house in Vietnam

Solar collector: - Type: vacuum tube,

D58 mm- Number of

vacuum tube: 20- Absorption area:

2.64 m2

- Volume of storage tank: 200 liters

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water for a 5-person house in Vietnam

Cycle diagram of HWHP:

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water for a 5-person house in Vietnam

1st Prototype of HWHP- Compressor: Danfoss,

Model SC-10GH, Refrigerant R134a, S.V. 10.29cm3/rev.

- Evaporator: finned tube type- Condenser: Helical shape heat

exchanger with natural convective on water side, HE area 0.226 m2

- Expansion device: capillary tube- Volume of storage tank: 50 liters

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water for a 5-person house in Vietnam

2nd Prototype of HWHP- Compressor: Danfoss,

Model SC-10GH, Refrigerant R134a, S.V. 10.29cm3/rev.

- Evaporator: finned-tube type- Condenser: Helical shape heat

exchanger with natural convective on water side, HE area 0.32 m2

- Expansion device: capillary tube- Volume of storage tank: 50 liters

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water for a 5-person house in Vietnam

950 W condenser manufacture for 2nd Prototype

- Condenser type: Helical shape with natural convective on water side

- Outside diameter of coil: 90 mm- Height of coil: 550 mm- Number of revolution: 64- Total heat exchanger area: 0.32 m2

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water for a 5-person house in Vietnam

2nd Prototype of HWHP,Final installation

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water fora 220-room, 4-star hotel in Vietnam

Diagram of SHCS

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water fora 220-room, 4-star hotel in Vietnam

System specifications:- Location: Nha Trang city- Total volume of hot water storage: 30 m3 (variable volume)- Solar collector type: vacuum tube, D58 mm- Number of collector panel: 27- Number of vacuum tube per panel: 50- Total absorption area of collector panels: 186 m2

- Number x Heating capacity of a HWHP: 4 x 18.5 kW - Total heating capacity of HWHP: 74 kW (34.7% of usual

requirement of 213 kW)- Heating COP: 3.6- Daily hot water usage: 13.2 m3

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water fora 220-room, 4-star hotel in Vietnam

Cycle diagram of HWHP:- Compressor: Bitzer,

4CC-9.2Y, R134a, 370cm3/rev.

- Evaporator: finned-tube type- Condenser: shell-tube, “multi

body” heat exchanger type- HE area: 2.51 m2

- Expansion device: thermostatic expansion valve (Danfoss)

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water fora 220-room, 4-star hotel in Vietnam

18.5 kW condenser manufacture (total HE area 2.51 m2):- Diameter of shell (outer tube): 54 mm- Number of shell per heat exchanger: 10- Diameter of tube: 12.7 mm- Number of tube per shell/ per heat exchanger: 7/70

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water fora 220-room, 4-star hotel in Vietnam

1st Prototype of HWHP:- Height: 1450 mm- Width: 1135 mm- Depth: 550 mm

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

Prototype of SHCS to produce hot water fora 220-room, 4-star hotel in Vietnam

1st Prototype of HWHP:- Height: 1450 mm- Width: 1135 mm- Depth: 550 mm

Method proposed for saving energy in hot waterproduction in residential and hotel sectors canprovide hot water with very low energyconsumption.

This method can be implemented with reasonableinitial cost by reducing the heating capacity of HotWater Heat Pump (HWHP) down to 20.4% and34.7% for residential and hotel sectors, respectively.

Require further study to verify the HW supplyingcapability as well as to determine the paybackperiod of this method with various applications.

ConclusionsHANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)

THANK YOU FOR YOUR KIND ATTENTION!

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY (HUST)National R&D Project