Grantee Research Project Results

Final Report: Heating Attic Air for Space Heating and Dryer Applications Using Solar Thermal

EPA Grant Number: SU835329
Title: Heating Attic Air for Space Heating and Dryer Applications Using Solar Thermal
Investigators: Tam, Kawai , Vu, Samantha , Leyva, Juan , Coria, Vanessa , Rodriguez, Giancarlo , Sanders, Brandon , Parker, Jonathan , Kim, Ji Hwan
Institution: University of California - Riverside
EPA Project Officer: Hahn, Intaek
Phase: II
Project Period: August 15, 2012 through August 14, 2014 (Extended to August 14, 2017)
Project Amount: $89,933
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2012) Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Sustainable and Healthy Communities , P3 Challenge Area - Air Quality , P3 Awards , Sustainable and Healthy Communities

Objective:

The impetus of the project was to help reduce the energy costs to a low-income community located in Moreno Valley, California known as Victory Gardens (VG). The main goal was to create an eco-friendly alternative to dry clothes with the usage of renewable energy.  During the summer, Moreno Valley’s temperatures can exceed 100°F. The team sought to put these high temperatures towards a more sustainable use and proposed a design to find a more efficient way to capture this heat. According to the Department of Energy, residential energy consumption for space heating, water heating, and clothes drying is comprised of 25.6%, 13.0%, 3.3% respectively.¹ By maximizing the use of solar and thermal energy of the sun, these appliances will be less reliant on fossil fuel energy and will be operating under these greener conditions.  

The goal is to use the heat to dry clothes year-round and incorporate space heating during the cooler months of the year. To accomplish these goals the team developed a combined solar collector and thermal closet prototype which was subjected to testing during Phase 1 of the project. Desirable results were achieved and for Phase 2 of the project, a full-scale implementation of the prototype was designed and installed onto a home in Moreno Valley.  During the construction process of the full-scale system, another prototype was designed and built at the University of California, Riverside in a community garden known as R’ Garden (RG). We decided to implement the same solar thermal dryer closet design in RG with the convenience of having a prototype closer to UCR with less inconvenience for the homeowner on which students can test. With the same scope to maximize the use of solar thermal energy, the team also designed a water heating system with a sink to benefit the gardening community. This combined system is referred to as the Integrated Appliance System (IAS). Students and RG visitors now have a place to wash their hands or clean their harvested vegetation.

Prosperity

The main purpose of this project was to design an eco-friendly and cost-effective alternative to four commonly used appliances. The solar collection system would trap natural solar energy, heat up air or water, then use it for a dryer, space heater, humidifier and/or water heater. By using it towards theses different applications we are able to reduce household expenses related to energy consumption. The overall cost-effectiveness was based on initial costs that would differ in the IAS and conventional systems, energy consumption, appliance lifespan, and maintenance costs. Energy requirements for appliances were based on energy reports published by the Department of Energy.¹ Using a discount rate of 5%, the equivalent annual operating cost (EAOC) of the IAS is $508, in comparison to the equivalent annual cost of $846 for the conventional appliances evaluated over a 20-year period. This is a 40% savings over a 20-year period. With these long-term savings, the integrated appliance system proves to be economically reasonable for household consumers. The itemization of the costs over a 20-year period is provided in Table 1. 

Table 1: Economic comparison of IAS and conventional appliances

System	Initial Investment	Annual operating costs	Maintenance costs	EAOC (at 5% discount rate)
IAS	$4,500	$128	$10/year;  Water heater: $200/12 years1	$508
Conventional (Water Heater + Dryer + Space Heater)	$850	$7551	Dryer: $150/8 years; Water heater: $200/12 years1	$846

 

Planet  

By providing an alternative source of energy from solar radiation, this design reduces environmental impacts related to the burning of fossil fuels and carbon monoxide; thus, reducing greenhouse gas (GHG) emissions which contribute to global warming. California, alone, produced the emissions as seen in Table 2 in 2014.² In 2011, the EPA added dryers to its Energy Star program and calculated that if 25% of dryers sold in America were 10% more efficient, the first year’s savings alone would equal 86,000 MWh for electric dryers, 76 billion Btu for gas dryers, and 141 million lbs of CO₂.

Table 2: Energy Generated and Emissions in 2014 (California)⁴

Energy Generated	197,243,680 MWh
Emissions
SO2	5,334 US tons
NOx	23,056 US tons
CO2	54,587,169 US tons
CH4	6,680,665 lbs.

emissions.³ This reduction in emissions and energy consumption is an attempt to aid the state of California’s vision to utilize 33% of renewable energy by 2020.⁴

People

 Along with the economic and environmental benefits our project provides, we are aiming to improve the lives of those who use it. With the implementation of the system, many hazards associated with electric or gas dryers are eliminated, such as carbon monoxide poisoning and fires. With the reduction of NOx emissions, there will be a reduction of ground level ozone pollution. Ground level ozone is formed from the chemical reaction between NOx and volatile organic compounds in the presence of sunlight. Breathing ozone can cause a variety of health problems.⁵ In addition to these health benefits, people in the Riverside community will have access to the prototype at RG. All RG users will be able to use the hot water connected to the system as well as learn about the system through informational signs posted. 

Educational Tool

Our project includes an educational plan to engage intended users at VG and RG, and engineering students on campus. When the system is fully operational, engineering students can use the systems to showcase sustainability, and to learn about data collection, process analysis, and problem solving. In addition to analyzing the system, the students will have the opportunity to make adjustments and refine the process of thermal heating through testing. Having a prototype at RG allows future and current engineering students to learn the entire process of creating a prototype. From idea to completion, they are able to see the necessary steps and problem solving involved in designing a sustainable appliance system. After understanding the goal of the project and the theory behind it, the engineering students would also work on the project to increase the efficiencies of the air and water heating systems.

Summary/Accomplishments (Outputs/Outcomes):

The proposed goal for Phase 2 of the project was to construct solar thermal collectors and solar thermal closets for installation onto four homes in the Victory Gardens community. The proposed project was aimed to be completed by 2014. However, due to several factors out of the team’s control, the option for space heating had to be removed and a full-scale unit was installed on one home at VG. The majority of the goals outlined by the proposed schedule have been completed. The process began with the development of a blueprint design that outlined the specific details on ryer system. A partnership was established with the company CV Construction who agreed to take on the role of constructing the solar thermal closet dryer. Obtaining a building permit from the city for construction proved to be longer than expected, and delayed the project by over 2 years before the construction of the closet dryer commenced. The current team is glad to mention that the overall material construction of the solar thermal closet dryer system has been completed for one home in Victory Gardens. The essential components such as the fans, ducting, insulation, temperature/humidity sensors, and the solar thermal collector have been installed, the latter of which is shown in Figure 1.  A faceplate design has also been created with the purpose of securing all the electrical components, while also having a display easily accessible for the consumer. A physical button layout has been implemented onto the faceplate design, enabling a more user-friendly interaction with the Micro-Controller. We are currently working on getting the fans to work simultaneously using the Micro-Controller to get a fully operational system. The team will then focus on collecting data and testing the system’s performance.

 

 

 

Figure 1: Solar Thermal Collector Box how to construct the full-scale solar thermal closet at VG

Concurrently, while the solar thermal closet dryer was being built at VG, the construction of a similar prototype system was also being built at UCR, in a community garden, known as RG. The same principles derived from the solar closet dryer system at VG was kept and improved upon through the addition of a water heating system. The combination of both the air and water heating systems is called the Integrated Appliance System (IAS). The construction of the IAS prototype was completed based on last year’s design noted in the EPA annual progress report. Both the air and water systems are inside a tool shed insulated with a 2.5-inch R-Tech sheathing, providing an R-value of 16.7, similar to that of a house. The interior of the closet dryer is shown in Figure 2.

 

 

 

 

 

 

 

Figure 2: Solar Thermal Dryer Closet at RG

Five temperature/humidity sensors have been installed within  the air system and an additional five temperature sensors are installed throughout the water system. In order to get all of the electrical components running in both systems in the remote RG area, we installed a photovoltaic (PV) system, (Figure 3), consisting of four lead acid batteries, three inverters, and eight solar panels.  Power was then delivered to all of the prototype’s electrical components. After obtaining preliminary data, it was found that the solar thermal collector box was not heating air to the appropriate temperatures. Data taken during the month of May, on days when the weather was predominantly sunny and cloud cover was low, showed that air passing through the solar thermal collector reached a maximum temperature of 38°C from a starting ambient temperature of at least 21°C. Although we did manage to increase the temperature of the air in the system, we still did not meet the desired temperature of 50°C. The team soon discovered that the solar collector boxes were under-designed and were not as efficient as had been originally predicted. Upon this discovery, the team redesigned an entirely new solar collector box that accounted for additional insulation properties and sufficient pipe length, which the old solar collector boxes failed to to adjust the air flow through the system. Currently, the new solar thermal collector box has been built and installed on the prototype shed, waiting to be tested (Figure 3). 

 

 

 

 

Figure 3: RG prototype meet. Along with the new box, the team purchased new fans

Although, we were able to receive some readings for our air system we ran into technical difficulties and were unable to draw in enough power to measure the temperatures for our water system. The issue was identified to be the inverters used in the PV system. The faulty inverters were sent back to the vendor and the team is still waiting for replacements to arrive. Since the IAS prototype is located in an area where power is inaccessible, testing could not be done on both air and water systems. 

A new solar box was designed to encase the copper solar coils of the water system. With the addition of this new solar coil box, the water is expected to reach higher temperatures than the original design with added insulation. The new solar coil box has been installed on the prototype shed (Figure 3). In the latest tests during November, average temperatures in Riverside, CA, ranged between 16℃ to 27℃, with days being mostly cloudy. Starting with an ambient temperature of 21℃ on a cloudy day, the solar coil box was able to increase the temperature of the water from 26.8℃ to 31℃ in 10 minutes. This was promising on a cloudy day. However, the temperature was not sustained over the next four hours. Insulation will be added to the PEX water pipes since recirculation of the water through the system results in potential heat losses. Additional insulation will be added to the solar coil box and the flowrate of the pump will be reduced. These adjustments will counteract the potential performance inhibiting factors. Theoretically, when the weather is sunny and ambient temperatures are above 27℃, the team expects the solar coil box to perform at its maximum potential and achieve temperatures of at least 43℃. 

In addition to the air and water heating units, the programming of the embedded systems has been completed. The process control system for the solar thermal closet dryer at VG and RG are almost exactly the same, with the exception of the attic portion at VG (Figure 4). The process commences by drawing in ambient air through an attic using an inline fan. The air is then directed into the solar thermal collector for heating. The heated air leaves the solar thermal collector, and travels through an air filtration system before entering the dryer closet. The air filtration system prevents dirt from contaminating the clothes inside the closet. The hot air will then enter the closet dryer from the bottom center allowing the hot air to rise uniformly and dry clothes. An outlet fan located at the top of the closet will draw the rising hot air out of the unit and release it back into the atmosphere. The Micro-controller is the most essential component of this system and without it this process would not be possible. 

 

Figure 4: Process control system for VG prototype

The Micro-Controller serves multiple functionalities and it is considered the system’s control center. All the system's electrical components such as the temperature and humidity sensors (T/H) and fans, tie into the Micro-Controller. Equipped with a physical button layout and touch screen LCD display, the Micro-Controller, allows a user to not only turn the system on and off, but also to adjust the system’s settings to conform to the user’s drying needs. Simultaneously, while the system is operating, the Micro-Controller records temperature and humidity data and uses this information to communicate and control the system's inlet and outlet fan speeds to achieve the most optimal drying conditions. Preset settings and safety precautions, such as the integration of an emergency shut off button, have been integrated onto the MicroController for a safer and more user-friendly experience.  

 

 

 

 

 

 

 

 

Figure 5: Solar thermal water system at RG

Just like the solar thermal closet dryer, the Micro-Controller is also being used as the water heating system’s process control center. The process for the solar thermal water system begins with city water being drawn towards the first electric water heater, which is mainly used as a water storage tank (Figure 5 - Items 1 & 2). The electric pump then draws water from this tank, and pumps the water through the solar coils (Figure 5 - Item 3). After the water is heated by the solar-heating coils, it will then be split into two streams (Figure 5 - Item 4). One stream will lead back to the same storage tank (Figure 5 - Item 2) for recirculation and further heating while the other stream will lead to the second electric water heater (Figure 5 - Item 5). Hot water can then be drawn from the second water heater for the consumer’s desired use. The hot water is heated to at least 50 °C to prevent bacterial growth but the desired temperature is 60 °C to kill any bacteria present in the water.⁶ In addition, safety precautions have been implemented for both water heaters to prevent the water from ever reaching temperatures below 50 °C. A programmed solenoid valve (Figure 5 - Items S) will be used to stop the water from entering water heater #2. This will create a closed loop between water heater #1 and the solar coils. The electrical pump (Figure 5 - Item E.P) will allow for the water to recycle multiples times and achieve higher temperatures. Once the water has attained the desired temperature, the solenoid valve will open, allowing water to pass into water heater #2. It must be noted that safety precautions have been accounted to prevent the water heaters from running out of water through the manipulation of the solenoid valve. An air release valve (Figure 5 - Item A.R.V) has also been installed to prevent air pockets from damaging the electric pump. 

Conclusions:

The main goals of this project were to reduce the energy demand for homes using solar thermal energy and to understand its overall effect on people, prosperity, and the planet. This project pushes for progress in sustainability, shifting from the dependence on nonrenewable energy sources to solar energy. Solar thermal energy is utilized for common home appliances such as space heating and clothes drying. This allows people to understand that this shift towards sustainability will not compromise the comfort aspect of living in addition to the possible electricity savings and other benefits to the planet. Furthermore, this project has allowed the university to interact with the neighboring community to promote solar thermal energy and encourage sustainability. 

 The goals of this project have been well established and will soon be fully met. At RG, with the addition of the new solar thermal collector and solar coil boxes, we are anticipating improved temperatures on not only the water system but also the drying closet. The IAS has an estimated 40% savings over a period of 20 years as previously highlighted in the Prosperity section. This large amount of savings is driven by the high price of electricity; $0.1739 per kWh in California.⁷ A standard dryer uses 967.0 kWh per year while the solar thermal closet dryer would consume only 64.4 kWh per year; this is an electricity savings of 93%. Since the full-scale VG unit only has the solar thermal closet dryer installation, this is the potential electricity savings realizable by the user of the full-scale solar thermal closet dryer. 

 The final component of the project is to have full integration of the Micro-Controller to the appliances. Once the system can be adequately controlled via one microcontroller, the system is anticipated to hit all of the benchmarks with the new solar collecting boxes, fans, and sensors at the RG installation, and the solar thermal closet dryer at VG. At VG, once the MicroController is installed on the solar thermal closet dryer in Moreno Valley, we will be able to get data on drying efficiencies on the full-scale unit. The unit is programmed to provide energy efficiency reports that the user can check. With the mindset of being not only environmentallyfriendly but also user-friendly, the team has taken steps to ensure full support to the consumer. Manuals have been created to teach the consumer how to run, troubleshoot, microcontroller reset, total system reset, and perform maintenance such as glass cleaning. Through the system’s configuration, manuals, and overall cost, the system has the potential to fulfill the original proposal’s goals of achieving sustainable appliances. This will be a showcase in the VG community to educate them on sustainability and energy efficiency. Similarly at RG, all users of the community garden will benefit from the hot water availability in this remote area and will be able to learn about the P3 project and sustainability of the IAS powered by solar energy. 

References:

1. United States, Congress, LaRose, Angelina, et al. “Annual Energy Outlook 2017.” Annual Energy Outlook 2017, Department of Energy, 5 Jan. 2017.
2. “Emissions & Generation Resource Integrated Database (EGRID).” Energy and the Environment, Environmental Protection Agency, 27 Feb. 2017,
3. “ENERGY STAR Market & Industry Scoping Report Residential Clothes Dryers.” Energy Star, Nov. 2011, pp. 1–18 
4. “Renewable Energy Program.” California Renewable Energy Overview and Programs. Web. 13 Mar. 2012. 
5. "Ozone Basics.” Ozone Pollution, Environmental Protection Agency, 5 Apr. 2017,
6. Lévesque, Benoît, Michel Lavoie, and Jean Joly. "Residential Water Heater Temperature: 49 or 60 Degrees Celsius?" The Canadian Journal of Infectious Diseases. Pulsus Group Inc, 2004. Web. 11 Nov. 2016.
7. “U.S. Energy Information Administration - EIA - Independent Statistics and Analysis.” Electric Sales, Revenue, and Average Price 2016 - Energy Information Administration, U.S. Energy Information Administration, 6 Nov. 2017

Journal Articles:

No journal articles submitted with this report: View all 1 publications for this project

Supplemental Keywords:

alternatives, residential, home improvement, energy saving, innovative technology, pollution prevention, ambient air, renewable, public good, cost-benefit

Progress and Final Reports:

Original Abstract

2013 Progress Report

2014 Progress Report

2015 Progress Report

2016 Progress Report

P3 Phase I:

Heating Attic Air Using Solar Thermal Energy for Space Heating and Drying Applications  | Final Report