Design of a solar water heating system for Alexandria, Egypt

The purpose of this work is two-fold. First, to introduce a comparison between steady state and dynamic test methods for two different collectors. Second, to design a solar water heating system to satisfy both hot water and space heating demands for a multi-family house in Alexandria, Egypt.     

Investigation of thermal performance of a ground coupled heat pump system with a cylindrical energy storage tank

An analytical and computational model for a solar assisted heat pump heating system with an underground seasonal cylindrical storage tank is developed. The heating system consists of flat plate solar collectors, an underground cylindrical storage tank, a heat pump and a house to be heated during winter season. Analytical solution of transient field problem outside the storage tank is obtained by the application of complex finite Fourier transform and finite integral transform techniques. Three expressions for the heat pump, space heat requirement during the winter season and available solar energy are coupled with the solution of the transient temperature field problem. The analytical solution presented can be utilized to determine the annual variation of water temperature in the cylindrical store, transient earth temperature field surrounding the store and annual periodic performance of the heating system. A computer simulation program is developed to evaluate the annual periodic water and earth temperatures and system performance parameters based on the analytical solution. Copyright © 2003 John Wiley & Sons, Ltd.     

Experimental study on house cooling and heating with solar energy using flat plate collector

The OSE Project aims at developing the technology to utilize solar energy for heating, cooling and hot water supply on the basis of various technology for energy conservation in buildings. For the first step of this project a solar heating and cooling system with flat plate collectors and absorption refrigeration machine was installed in a house in 1974. This paper reports outlines of the system and operating results.     

Solar operated absorption air-conditioner for a Kufra house

The use of solar energy for domestic water heating and space heating has proved to be viable. Space cooling is another promising avenue for utilization of solar energy. Solar operated absorption air-conditioning systems, in different situations, have been found to be feasible. Such systems can make use of the expensive collectors which are, in any case, installed for water and space heating.

In this paper the cooling of a prototype house, in Kufra, is reported. Starting with measured radiation and ambient data, calculations are performed on an hourly basis to determine the cooling load, radiation in the collector plane, heat delivered by the collectors and the heat stored in or discharged from the storage tank. Three different types of collectors with varying efficiencies are considered. These collectors are of the evacuated tube, selective coated and black painted types. The study confirms that the water-lithium bromide absorption system can provide summer air conditioning in arid zones of Jamahiriya where there are diffuclties with the supply of electricity and fossil fuels.     

Computational evaluation of solar heating systems using concrete solar collectors

This paper uses the F-chart technique to evaluate three types of solar heating systems, namely; space solar heating and domestic hot water system (SHDHW), domestic hot water system (DHW) and solar swimming pool heating system (SPHS), using three types of concrete solar collectors, models A, B, and C, and one conventional metallic solar collector.

The economical analysis of SHDHW system revealed that the concrete collectors provided about 49 and 63% of the annual load when the collecting area of the solar panel increased from 55 to 88 M² (25 to 40% of the building roof area). The corresponding solar contributions when conventional metallic collectors were used are 41 and 53%, respectively. This represents an improvement of the annual solar fraction of about 19% when concrete collectors are used instead of the metallic collectors.

It was found that solar heating systems with concrete solar collector models gave higher solar fractions and total life cycle savings than the conventional solar metallic collector.     

Status and prospects of local solar heating and cooling systems

In this paper, a state-of-the-art of solar heating and cooling systems is presented. Solar air heaters and different types of solar water collectors are discussed in detail. Storage systems including water, rocks, and heat-of-fusion salts are described as are space heating systems employing solar air heaters, in conjunction with rock or heat-of-fusion salt storage, and the use of water collectors plus hot water storage for space heating and domestic hot water. An indication of the commercialization of various space-heating systems and broad economic projections are presented. The three major solar cooling methods—absorption cooling, solar mechanical systems, and those involving humidification-dehumidification cycles—are also discussed in detail. Finally, an overview of solar heating and cooling activities in Kuwait is also given.     

Energy resource requirements of a solar heating system

The methods of energy analysis have been applied to a liquid-based, short-term storage solar space and water heating system suitable for a single family dwelling in Toronto. This system, which in many respects represents a worst case for solar heating, takes 1.0–3.5 years of operation to conserve the energy resources required to build, operate and maintain the system. Alternatively, over the twenty year lifetime of the system, the energy resources used indirectly by the solar heating system amount to between 6 and 24% of the direct energy resources conserved by the system. These considerations do not significantly alter the energy-conservation characteristics of the solar heating system unless thermally-generated electricity is used as backup for a 50% solar heating system which replaces oil or gas heating; in this case, only 4–9% of the energy resources are conserved by the solar system. A factor of three variation in energy resource use in collector materials was found in a sample of 7 flat-plate collectors with steel-based collectors using the least. The total energy embodied in the collector was about double that found in the materials alone. The collectors and annual operating energy for the pumps were found to be the two most significant factors in the analysis. An appendix summarizes the energy resource requirements embodied in the materials used for collectors.     

Solar space heating and air conditioning in the Thomason Home

The problems of successful solar space heating are many and varied. The scientist and engineer who starts out merely to heat his home by solar energy, with presently known apparatus and materials, faces a very difficult situation because the amount of heat energy received per square foot of surface per heating season is quite low, and the cost of previous efficient solar heat collectors has been high. Further problems are involved because the solar input occurs only about 6 hrs out of 24, and because many cloudy days per season plague the solar scientist. This paper reports the author's attempts to solve these difficult problems of solar space heating and cooling.     

Identifying key design parameters of the integrated energy system for a residential Zero Emission Building in Norway

This study examined an integrated solution of the building energy supply system consisting of flat plate solar thermal collectors in combination with a ground-source heat pump and an exhaust air heat pump for the heating and cooling, and production of domestic hot water. The supply energy system was proposed to a 202 m² single-family demo dwelling (SFD), which is defined by the Norwegian Zero Emission Building standard. The main design parameters were analyzed in order to find the most essential parameters, which could significantly influenced the total energy use. This study found that 85% of the total heating demand of the SFD was covered by renewable energy. The results showed that the solar energy generated by the system could cover 85–92% and 12–70% of the domestic hot water demand in summer and winter respectively. In addition, the solar energy may cover 2.5–100% of the space heating demand. The results showed that the supply air volume, supply air and zone set point temperatures, auxiliary electrical volume, volume of the DHW tank, orientation and tilt angle and the collector area could influenced mostly the total energy use.     

Efficiency of solar energy use for residential heating and cooling

The possibility of using solar energy collected on flat plate collectors situated on roofs for residential space heating/cooling and domestic water heating is considered. The study is carried out on a typical house situated in various locations in Libya. Two types of constructions involving heavy and light insulation, three roof tilts, and three values of system efficiency are considered. The study shows that the demand in a great part of the country can be provided from solar energy by a medium efficiency system, even with light insulation and a horizontal roof. Only in a few locations should the roof be tilted at an angle of 10 °. For a low-efficiency system, insulation is necessary; for a high-efficiency-system, it was found that there is no need for either heavy insulation or tilting of the roof.     

Parametric Analysis of Solar Heating and Cooling Systems for Residential Applications

Abstract

In this paper, a parametric analysis of two solar heating and cooling systems, one using an absorption heat pump and the other one using an adsorption heat pump, was performed. The systems under investigation were designed to satisfy the energy requirements of a residential building for space heating/cooling purposes and domestic hot water production. The system with the absorption heat pump was analyzed upon varying (i) the solar collectors’ area, (ii) the volume of the hot water storage, (iii) the volume of the cold water tank, and (iv) the climatic conditions. The system with the adsorption heat pump was evaluated upon varying (i) the inlet temperature of hot water supplied to the adsorption heat pump, (ii) the volume of the hot water storage, (iii) the volume of the cold water tank, and (iv) the climatic conditions. The analyses were performed using the dynamic simulation software TRNSYS in terms of primary energy consumption, global carbon dioxide equivalent emissions, and operating costs. The performance of the solar heating and cooling systems was compared with those associated with a conventional system from energy, environmental and economic points of views in order to evaluate the potential benefits.     

The performance of a solar water heating system in a dwelling in Christchurch, New Zealand

Tests have been made on a solar water heating system installed in a house in Christchurch, New Zealand. The system consisted of commercially-available flat plate collectors connected in a natural circulation loop to an insulated storage tank with electric booster heating. System temperatures, insolation, electricity consumption, hot water usage and circulation flow rates were measured and recorded on a Cassesse-Tape Data Logger, and the data were processed on the Department's mini-computer. Information has been obtained on insolation on an inclined surface and on hot water consumption patterns, as well as on the solar system performance.     

Aspects and improvements of hybrid photovoltaic/thermal solar energy systems

Hybrid photovoltaic/thermal (PV/T or PVT) solar systems consist of PV modules coupled to water or air heat extraction devices, which convert the absorbed solar radiation into electricity and heat. At the University of Patras, an extended research on PV/T systems has been performed aiming at the study of several modifications for system performance improvement. In this paper a new type of PV/T collector with dual heat extraction operation, either with water or with air circulation is presented. This system is simple and suitable for building integration, providing hot water or air depending on the season and the thermal needs of the building. Experiments with dual type PV/T models of alternative arrangement of the water and the air heat exchanging elements were performed. The most effective design was further studied, applying to it low cost modifications for the air heat extraction improvement. These modifications include a thin metallic sheet placed in the middle of the air channel, the mounting of fins on the opposite wall to PV rear surface of the air channel and the placement of the sheet combined with small ribs on the opposite air channel wall. The modified dual PV/T collectors were combined with booster diffuse reflectors, achieving a significant increase in system thermal and electrical energy output. The improved PV/T systems have aesthetic and energy advantages and could be used instead of separate installation of plain PV modules and thermal collectors, mainly if the available building surface is limited and the thermal needs are associated with low temperature water or air heating.     

Assessment and modelling of the viability of a solar heating system for aquatic centres in southern Australia

Aquatic centres are large users of energy for water and space heating with an energy intensity which can be up to seven times that of a commercial office building in Australia. Much of the energy is used to heat water to relatively low temperatures, and therefore, solar energy technology is capable of providing this energy. In the residential sector, solar thermal systems for heating water and swimming pools are well-established. This is not the case for commercial swimming pools i.e. aquatic centres. In Australia, a program to encourage commercial pool operators to install solar systems was funded in the early 1980s. This paper has investigated the current use of and attitudes to solar systems in commercial pools through a survey of municipal pool operators in Victoria, southern Australia. The survey found that there has been very little increase in the use of solar energy and that perceived barriers to the use of the technology remain the same as they were nearly 30 years ago. Lack of roof area, poor payback periods and an inability of solar to meet pool heating needs are the most common misconceptions. The paper investigates these misconceptions by analysing the hot water needs of a large aquatic centre in Melbourne. It was found that there was sufficient roof area to accommodate a solar system that would provide a solar fraction of 0.60 and the simple payback period for a solar system using unglazed solar collectors was approximately 6.7 years at current gas prices. These are predicted to rise significantly making solar energy an even more attractive proposition for commercial pool heating. Failure of past incentives to stimulate the uptake of solar pool heating systems necessitates a revised approach. Key stakeholders (industry bodies, local governments, pool operators, manufacturers, relevant HVAC consultants and research organisations) all need to be involved in an exemplar project to demonstrate the technology’s viability for aquatic centres.     

Increasing solar gains by using hot water to heat dishwashers and washing machines

Seventy to ninety percent of the electric energy used by dishwashers and washing machines heats the water, the crockery, the laundry and the machine and could just as well be replaced by heating energy from solar collectors, district heating or a boiler. A dishwasher and a washing machine equipped with a heat exchanger and heated by a hot water circulation circuit instead of electricity (heat-fed machines) have been simulated together with solar heating systems for single-family houses in two different climates (Stockholm, Sweden and Miami, USA). The simulations show that a major part of the increased heat load due to heat-fed machines can be covered by solar heat both in hot and cold climates if the collector area is compensated for the larger heat load to give the same marginal contribution. Using ordinary machines connected to the hot water pipe (hot water-fed machines) and using only cold water for the rinses in the washing machine gives almost the same solar contribution; however considerably lower electrical energy savings are achieved. The simulations also indicate that improvements in the system design of a combisystem (increased stratification in the store) are more advantageous if heat-fed machines are connected to the store. Thus, using heat-fed machines also encourages the use of more advanced solar combisystems.     

Advanced energy-efficient house (HARBEMAN house) with solar thermal, photovoltaic, and sky radiation energies (experimental results)

An energy-independent residential house (‘HARBEMAN house’; Harmony BEtween Man And Nature), incorporating sky radiation cooling, solar thermal, and photovoltaic energies was built in Sendai, Japan during July, 1996. This paper reports monitored results of this house since September 1996 to date. The paper also presents simulation results for the HARBEMAN house and its results compared with the annual experimental data. The HARBEMAN house, which meets almost all the energy demands, including space heating and cooling, domestic hot water, electricity generated by photovoltaic cell and rainwater for standard Japanese homes. Sky radiation cooling, solar thermal/photovoltaic (PV), and underground coolness as well as rainwater and waste heat are utilized in combination. Annual variations of water temperature in the underground main tank, heating/cooling/domestic hot water demands, collected and emitted heats by the solar collector and sky radiator have been monitored.     

Simulation analysis for the active solar heating system of a passive house

The active solar heating system consists of the following sub-systems: (1) a solar thermal collector area, (2) a water storage tank, (3) a secondary water circuit, (4) a domestic hot water (DHW) preparation system and (5) an air ventilation/heating system. An improved model for the secondary water circuit is proposed and two interconnection schemes for sub-systems (4) and (5) are analyzed. The integrated model was implemented to Pirmasens passive house (Rhineland Palatinate, Germany). Both interconnection schemes show that (almost all) the solar energy collected is not used for space heating but for domestic hot water preparation. The classical water heater operates all over the year and the classical air heater operates mainly during the nights from November to April. The yearly amount of heat required by the DHW preparation system is about 77% of the yearly total heat demand of the passive house and the classical water heater provides about 20% of the yearly heat required by the DHW preparation system. The solar fraction lies between 0.247 in January and 0.930 in August, with a yearly average of 0.597.     

A solar thermal cooling and heating system for a building: Experimental and model based performance analysis and design

A solar thermal cooling and heating system at Carnegie Mellon University was studied through its design, installation, modeling, and evaluation to deal with the question of how solar energy might most effectively be used in supplying energy for the operation of a building. This solar cooling and heating system incorporates 52 m² of linear parabolic trough solar collectors; a 16 kW double effect, water-lithium bromide (LiBr) absorption chiller, and a heat recovery heat exchanger with their circulation pumps and control valves. It generates chilled and heated water, dependent on the season, for space cooling and heating. This system is the smallest high temperature solar cooling system in the world. Till now, only this system of the kind has been successfully operated for more than one year. Performance of the system has been tested and the measured data were used to verify system performance models developed in the TRaNsient SYstem Simulation program (TRNSYS). On the basis of the installed solar system, base case performance models were programmed; and then they were modified and extended to investigate measures for improving system performance. The measures included changes in the area and orientation of the solar collectors, the inclusion of thermal storage in the system, changes in the pipe diameter and length, and various system operational control strategies. It was found that this solar thermal system could potentially supply 39% of cooling and 20% of heating energy for this building space in Pittsburgh, PA, if it included a properly sized storage tank and short, low diameter connecting pipes. Guidelines for the design and operation of an efficient and effective solar cooling and heating system for a given building space have been provided.