THE LONG ROAD TO DECARBONIZATION
DESIGN AND DEVELOPMENT OF AN ACTIVE SOLAR THERMAL SPACE/WATER HEATING SYSTEM
By Hamza Javaid, Muhammad Bilal Khan, Abdul Waheed Badar, Uzair Bin Nusair, Abdul Wahab, Muhammad Zeeshan Siddique
Abstract
Space heating in Pakistan is largely based on natural gas and/or electrically run heaters/reversible ACs. Solar space-heating systems are usually combined with water heating and they are sized to accommodate both uses. The selection and sizing of combined solar space and water heating systems is quite a complex problem involving many interrelated factors and design variables.
The main key components of any active solar space heating system are the radiator/fan coil unit, storage tank, heat exchanger and solar thermal collector. The project’s main objective is to design and develop a small-scale fully functional solar thermal space/water heating system. For this purpose, a heating system has been designed through an iterative procedure performed analytically and using a transient simulation program (TRNSYS), which is used to correlate the system’s thermal performance with several key design parameters.
Based on the results of mathematical simulations, optimum-sized components of the whole system have been manufactured/purchased and fabricated to meet a heating load of 3.5 kW. Real-time experimentations were carried out by measuring temperature, flow rates and energy transfers to ascertain the thermal performance of the system.
Introduction
Space heating in Pakistan is largely based on natural gas and/or electrically run heaters/reversible ACs. Solar space-heating systems are usually combined with water heating and they are sized to accommodate both uses. The selection and sizing of combined solar space and water heating systems is quite a complex problem involving many interrelated factors and design variables.
The main key components of any active solar space heating system are the radiator/fan coil unit, storage tank, heat exchanger and solar thermal collector. The project’s main objective is to design and develop a small-scale fully functional solar thermal space/water heating system.
System Description
The schematic layout consists of:
Flat plate collector (FPC)
Evacuated tube collector (ETC)
Hot storage tank
Auxiliary heater
Fan coil unit
Controllers
Pumps
Hot water produced by FPC and ETC is stored in a stratified tank. Auxiliary heaters maintain water temperature (≈50°C) when solar heat is insufficient. A differential controller operates pumps only when outlet temperature exceeds inlet temperature.
Transient Modeling
TRNSYS 18.0 was used to simulate system behavior under Taxila climate (33.74°N, 72.83°E) for a 3.5kW heating load. Simulations correlated various system design choices with thermal performance.
Manufacturing and Fabrication
Collector configuration: 1 FPC (2 m²) + 2 ETC (1.5 m² each)
Hot water tank: 25 gallons, cast iron, glass wool insulation
Fan coil: 1 TR (3.5 kW)
Pumps: 0.5 hp centrifugal pumps
Copper piping (¾ inch)
Experimental Results
Experiments conducted on a winter day in December:
Max collector outlet temperature: ~45°C (~20°C above ambient)
Flow rates, temperature profiles and energy transfer were monitored
Cost Analysis
Complete cost table is provided in the PDF, with total system cost ≈ PKR 859,601.
Conclusions
The developed system meets a 3.5 kW heating load with optimized collector area, storage volume, flow rate and fan coil sizing. The project provides a working educational and research model for solar thermal heating solutions.